diff --git a/include/cantera/kinetics/Arrhenius.h b/include/cantera/kinetics/Arrhenius.h
index 400dc0e2ba1..c1a798f79a2 100644
--- a/include/cantera/kinetics/Arrhenius.h
+++ b/include/cantera/kinetics/Arrhenius.h
@@ -44,7 +44,7 @@ class ArrheniusBase
 
     //! Constructor based on AnyValue content
     ArrheniusBase(const AnyValue& rate,
-                  const UnitSystem& units, const Units& rate_units)
+                  const UnitSystem& units, const UnitsVector& rate_units)
     {
         setParameters(rate, units, rate_units);
     }
@@ -56,11 +56,17 @@ class ArrheniusBase
      *  @param rate_units  Unit definitions specific to rate information
      */
     virtual void setParameters(const AnyValue& rate,
-                               const UnitSystem& units, const Units& rate_units);
+                               const UnitSystem& units, const UnitsVector& rate_units);
 
-    //! Get parameters
-    //! Store the parameters of a ReactionRate needed to reconstruct an identical
-    virtual void getParameters(AnyMap& node, const Units& units) const;
+    //! Return parameters
+    /*!
+     *  @param node  AnyValue containing rate information
+     */
+    virtual void getParameters(AnyMap& node) const;
+
+    //! Return parameters - required for legacy framework
+    //! @todo: merge with single-parameter version after removal of old framework
+    virtual void getParameters(AnyMap& node, const Units& rate_units) const;
 
     //! Validate the reaction rate expression
     virtual void validate(const std::string& equation);
@@ -87,10 +93,24 @@ class ArrheniusBase
 
     size_t rate_index; //!< Reaction rate index within kinetics evaluator
 
+    void setRateUnits(const UnitsVector& rate_units) {
+        m_rate_units = Units::product(rate_units);
+        if (rate_units.size()>1) {
+            m_order = 0;
+            for (size_t i = 2; i < rate_units.size(); ++i) {
+                m_order -= rate_units[i].second;
+            }
+        } else {
+            m_order = NAN;
+        }
+    }
+
 protected:
     double m_A; //!< Pre-exponential factor
     double m_b; //!< Temperature exponent
     double m_Ea_R; //!< Activation energy (in temperature units)
+    double m_order; //!< Reaction order
+    Units m_rate_units; //!< Reaction rate units
 };
 
 
@@ -115,7 +135,7 @@ class Arrhenius3 : public ArrheniusBase
     using ArrheniusBase::setParameters;
 
     //! Constructor based on AnyMap content
-    Arrhenius3(const AnyMap& node, const Units& rate_units) {
+    Arrhenius3(const AnyMap& node, const UnitsVector& rate_units) {
         setParameters(node, rate_units);
     }
 
@@ -129,9 +149,9 @@ class Arrhenius3 : public ArrheniusBase
      *  @param node  AnyMap containing rate information
      *  @param rate_units  Unit definitions specific to rate information
      */
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
-    virtual void getParameters(AnyMap& node, const Units& units) const;
+    virtual void getParameters(AnyMap& node) const;
 
     //! Update information specific to reaction
     const static bool usesUpdate() {
@@ -219,7 +239,7 @@ class BlowersMasel3 : public ArrheniusBase
     BlowersMasel3(double A, double b, double Ea0, double w);
 
     //! Constructor based on AnyMap content
-    BlowersMasel3(const AnyMap& node, const Units& rate_units) {
+    BlowersMasel3(const AnyMap& node, const UnitsVector& rate_units) {
         setParameters(node, rate_units);
     }
 
@@ -229,16 +249,16 @@ class BlowersMasel3 : public ArrheniusBase
     }
 
     virtual void setParameters(const AnyValue& rate,
-                               const UnitSystem& units, const Units& rate_units);
+                               const UnitSystem& units, const UnitsVector& rate_units);
 
     //! Perform object setup based on AnyMap node information
     /*!
      *  @param node  AnyMap containing rate information
      *  @param rate_units  Unit definitions specific to rate information
      */
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
-    virtual void getParameters(AnyMap& node, const Units& units) const;
+    virtual void getParameters(AnyMap& node) const;
 
     //! Update information specific to reaction
     const static bool usesUpdate() {
diff --git a/include/cantera/kinetics/Falloff.h b/include/cantera/kinetics/Falloff.h
index 3a8eba65c96..03f6e5c7893 100644
--- a/include/cantera/kinetics/Falloff.h
+++ b/include/cantera/kinetics/Falloff.h
@@ -132,7 +132,7 @@ class Falloff
     //! Perform object setup based on AnyMap node information
     //! @param node  AnyMap containing rate information
     //! @param rate_units  unit definitions specific to rate information
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
     //! Get the values of the parameters for this object. *params* must be an
     //! array of at least nParameters() elements.
@@ -141,14 +141,9 @@ class Falloff
      */
     virtual void getParameters(double* params) const {}
 
-    /**
-     * @todo  deprecate; only used by legacy framework
-     */
-    virtual void getParameters(AnyMap& reactionNode) const {}
-
     //! Store the falloff-related parameters needed to reconstruct an identical
     //! Reaction using the newReaction(AnyMap&, Kinetics&) function.
-    virtual void getParameters(AnyMap& rateNode, const Units& rate_units) const;
+    virtual void getParameters(AnyMap& reactionNode) const;
 
     //! Flag indicating that information specific to reaction rate is required
     const static bool usesUpdate() {
@@ -315,7 +310,7 @@ class Troe : public Falloff
         return 4;
     }
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
     //! Sets params to contain, in order, \f[ (A, T_3, T_1, T_2) \f]
     /**
@@ -325,8 +320,6 @@ class Troe : public Falloff
 
     virtual void getParameters(AnyMap& reactionNode) const;
 
-    virtual void getParameters(AnyMap& rateNode, const Units& rate_units) const;
-
 protected:
     //! parameter a in the 4-parameter Troe falloff function. Dimensionless
     double m_a;
@@ -402,7 +395,7 @@ class SRI : public Falloff
         return 5;
     }
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
     //! Sets params to contain, in order, \f[ (a, b, c, d, e) \f]
     /**
@@ -412,8 +405,6 @@ class SRI : public Falloff
 
     virtual void getParameters(AnyMap& reactionNode) const;
 
-    virtual void getParameters(AnyMap& rateNode, const Units& rate_units) const;
-
 protected:
     //! parameter a in the 5-parameter SRI falloff function. Dimensionless.
     double m_a;
@@ -495,7 +486,7 @@ class Tsang : public Falloff
         return 2;
     }
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& rate_units);
 
     //! Sets params to contain, in order, \f[ (A, B) \f]
     /**
@@ -505,8 +496,6 @@ class Tsang : public Falloff
 
     virtual void getParameters(AnyMap& reactionNode) const;
 
-    virtual void getParameters(AnyMap& rateNode, const Units& rate_units) const;
-
 protected:
     //! parameter a in the Tsang F_cent formulation. Dimensionless
     double m_a;
diff --git a/include/cantera/kinetics/ReactionRate.h b/include/cantera/kinetics/ReactionRate.h
index 325f039d8a4..e0e7933fa90 100644
--- a/include/cantera/kinetics/ReactionRate.h
+++ b/include/cantera/kinetics/ReactionRate.h
@@ -126,8 +126,8 @@ class RateTemplate : public ReactionRate<DataType>,  public RateType
     //! Constructor using AnyMap content
     //! @param node  AnyMap containing rate information
     //! @param rate_units  unit definitions used for rate information
-    RateTemplate(const AnyMap& node, const Units& rate_units=Units(0.)) {
-        setParameters(node, rate_units);
+    RateTemplate(const AnyMap& node, const UnitsVector& units={}) {
+        setParameters(node, units);
     }
 
     virtual const std::string type() const override {
@@ -135,13 +135,13 @@ class RateTemplate : public ReactionRate<DataType>,  public RateType
         return RateType::type();
     }
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units) override {
-        ReactionRateBase::setParameters(node, rate_units);
-        RateType::setParameters(node, rate_units);
+    virtual void setParameters(const AnyMap& node, const UnitsVector& units) override {
+        ReactionRateBase::setParameters(node, units);
+        RateType::setParameters(node, units);
     }
 
-    virtual void getParameters(AnyMap& node, const Units& rate_units) const override {
-        RateType::getParameters(node, rate_units);
+    virtual void getParameters(AnyMap& node) const override {
+        RateType::getParameters(node);
     }
 
     virtual unique_ptr<MultiRateBase> newMultiRate() const override {
@@ -240,8 +240,8 @@ class PlogRate final : public ReactionRate<PlogData>, public Plog
 
     //! Constructor using AnyMap content
     //! @param node  AnyMap containing rate information
-    //! @param rate_units  unit definitions used for rate information
-    PlogRate(const AnyMap& node, const Units& rate_units=Units(0.));
+    //! @param units  Description of units used for rate parameters
+    PlogRate(const AnyMap& node, const UnitsVector& units={});
 
     virtual const std::string type() const override {
         return "pressure-dependent-Arrhenius";
@@ -249,9 +249,8 @@ class PlogRate final : public ReactionRate<PlogData>, public Plog
 
     virtual unique_ptr<MultiRateBase> newMultiRate() const override;
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units) override;
-    virtual void getParameters(AnyMap& rateNode,
-                               const Units& rate_units) const override;
+    virtual void setParameters(const AnyMap& node, const UnitsVector& units) override;
+    virtual void getParameters(AnyMap& rateNode) const override;
 
     //! Update information specific to reaction
     static bool usesUpdate() { return true; }
@@ -324,16 +323,15 @@ class ChebyshevRate3 final : public ReactionRate<ChebyshevData>, public Chebyshe
 
     //! Constructor using AnyMap content
     //! @param node  AnyMap containing rate information
-    //! @param rate_units  unit definitions used for rate information
-    ChebyshevRate3(const AnyMap& node, const Units& rate_units=Units(0.));
+    //! @param units  Description of units used for rate parameters
+    ChebyshevRate3(const AnyMap& node, const UnitsVector& rate_units={});
 
     virtual const std::string type() const override { return "Chebyshev"; }
 
     virtual unique_ptr<MultiRateBase> newMultiRate() const override;
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units) override;
-    virtual void getParameters(AnyMap& rateNode,
-                               const Units& rate_units) const override;
+    virtual void setParameters(const AnyMap& node, const UnitsVector& units) override;
+    virtual void getParameters(AnyMap& rateNode) const override;
 
     //! Update information specific to reaction
     static bool usesUpdate() { return true; }
@@ -347,6 +345,9 @@ class ChebyshevRate3 final : public ReactionRate<ChebyshevData>, public Chebyshe
     }
 
     virtual void validate(const std::string& equation) override;
+
+protected:
+    Units m_rate_units; //!< Reaction rate units
 };
 
 
@@ -366,15 +367,15 @@ class CustomFunc1Rate final : public ReactionRate<CustomFunc1Data>
 
     //! Constructor does nothing, as there is no formalized parameterization
     //! @param node  AnyMap object containing reaction rate specification
-    //! @param rate_units  Description of units used for rate parameters
-    CustomFunc1Rate(const AnyMap& rate, const Units& rate_units) {}
+    //! @param units  Description of units used for rate parameters
+    CustomFunc1Rate(const AnyMap& rate, const UnitsVector& units) {}
 
     virtual const std::string type() const override { return "custom-rate-function"; }
 
     virtual unique_ptr<MultiRateBase> newMultiRate() const override;
 
-    virtual void setParameters(const AnyMap& node, const Units& rate_units) override {
-        units = rate_units;
+    virtual void setParameters(const AnyMap& node, const UnitsVector& units) override {
+        ReactionRateBase::setParameters(node, units);
     }
 
     //! Update information specific to reaction
diff --git a/include/cantera/kinetics/ReactionRateBase.h b/include/cantera/kinetics/ReactionRateBase.h
index 0cd303fc01a..c312b99977a 100644
--- a/include/cantera/kinetics/ReactionRateBase.h
+++ b/include/cantera/kinetics/ReactionRateBase.h
@@ -36,7 +36,7 @@ class Kinetics;
 class ReactionRateBase
 {
 public:
-    ReactionRateBase() : units(0.), m_idx(npos) {}
+    ReactionRateBase() : m_idx(npos) {}
     virtual ~ReactionRateBase() {}
 
 public:
@@ -94,32 +94,18 @@ class ReactionRateBase
     //! Return the parameters such that an identical Reaction could be reconstructed
     //! using the newReaction() function. Behavior specific to derived classes is
     //! handled by the getParameters() method.
-    //! @param rate_units  units used for rate parameters
-    AnyMap parameters(const Units& rate_units) const {
+    AnyMap parameters() const {
         AnyMap out;
-        getParameters(out, rate_units);
+        getParameters(out);
         return out;
     }
 
-    //! Return parameters using original unit system
-    AnyMap parameters() const {
-        return parameters(units);
-    }
-
     //! Set parameters
     //! @param node  AnyMap object containing reaction rate specification
-    //! @param rate_units  Description of units used for rate parameters
-    virtual void setParameters(const AnyMap& node, const Units& rate_units) {
-        units = rate_units;
+    virtual void setParameters(const AnyMap& node, const UnitsVector& units) {
         input = node;
     }
 
-    //! Set rate units
-    //! @param rate_units  Description of units used for rate parameters
-    virtual void setUnits(const Units& rate_units) {
-        units = rate_units;
-    }
-
     //! Reaction rate index within kinetics evaluator
     size_t rateIndex() const {
         return m_idx;
@@ -134,7 +120,7 @@ class ReactionRateBase
     //! Get parameters
     //! Store the parameters of a ReactionRate needed to reconstruct an identical
     //! object. Does not include user-defined fields available in the #input map.
-    virtual void getParameters(AnyMap& rateNode, const Units& rate_units) const {
+    virtual void getParameters(AnyMap& rateNode) const {
         throw NotImplementedError("ReactionRate::getParameters",
                                   "Not implemented by '{}' object.", type());
     }
@@ -142,11 +128,6 @@ class ReactionRateBase
     //! Input data used for specific models
     AnyMap input;
 
-    //! The units of the rate constant. These are determined by the units of the
-    //! standard concentration of the reactant species' phases of the phase
-    //! where the reaction occurs.
-    Units units;
-
     size_t m_idx; //!< Index of reaction rate within kinetics evaluator
 };
 
diff --git a/include/cantera/kinetics/RxnRates.h b/include/cantera/kinetics/RxnRates.h
index 57b5abe628a..68305db694a 100644
--- a/include/cantera/kinetics/RxnRates.h
+++ b/include/cantera/kinetics/RxnRates.h
@@ -34,7 +34,7 @@ class Units;
  *        k_f =  A T^b \exp (-E/RT)
  *   \f]
  */
-class Arrhenius2 : public ArrheniusBase
+class Arrhenius2 final : public ArrheniusBase
 {
 public:
     //! Default constructor.
@@ -335,7 +335,7 @@ class Plog
     void setParameters(const std::vector<AnyMap>& rates,
                        const UnitSystem& units, const Units& rate_units);
 
-    void getParameters(AnyMap& rateNode, const Units& rate_units) const;
+    void getParameters(AnyMap& rateNode, const Units& rate_units=Units(0.)) const;
 
     //! Set up Plog object
     /*!
diff --git a/src/kinetics/Arrhenius.cpp b/src/kinetics/Arrhenius.cpp
index 2e9c32dcea1..d00368b1b5c 100644
--- a/src/kinetics/Arrhenius.cpp
+++ b/src/kinetics/Arrhenius.cpp
@@ -15,6 +15,8 @@ ArrheniusBase::ArrheniusBase()
     , m_A(NAN)
     , m_b(NAN)
     , m_Ea_R(NAN)
+    , m_order(NAN)
+    , m_rate_units(Units(0.))
 {
 }
 
@@ -24,20 +26,28 @@ ArrheniusBase::ArrheniusBase(double A, double b, double Ea)
     , m_A(A)
     , m_b(b)
     , m_Ea_R(Ea / GasConstant)
+    , m_order(NAN)
+    , m_rate_units(Units(0.))
 {
 }
 
 void ArrheniusBase::setParameters(
-    const AnyValue& rate, const UnitSystem& units, const Units& rate_units)
+    const AnyValue& rate, const UnitSystem& units, const UnitsVector& rate_units)
 {
     if (rate.empty()) {
         m_A = NAN;
         m_b = NAN;
         m_Ea_R = NAN;
-    } else if (rate.is<AnyMap>()) {
+        m_order = NAN;
+        m_rate_units = Units(0.);
+        return;
+    }
+
+    setRateUnits(rate_units);
+    if (rate.is<AnyMap>()) {
 
         auto& rate_map = rate.as<AnyMap>();
-        if (rate_units.factor() == 0) {
+        if (m_rate_units.factor() == 0) {
             // A zero rate units factor is used as a sentinel to detect
             // stand-alone reaction rate objects
             if (rate_map["A"].is<std::string>()) {
@@ -47,7 +57,7 @@ void ArrheniusBase::setParameters(
             }
             m_A = rate_map["A"].asDouble();
         } else {
-            m_A = units.convert(rate_map["A"], rate_units);
+            m_A = units.convert(rate_map["A"], m_rate_units);
         }
         m_b = rate_map["b"].asDouble();
         if (rate_map.hasKey("Ea")) {
@@ -57,12 +67,17 @@ void ArrheniusBase::setParameters(
         }
     } else {
         auto& rate_vec = rate.asVector<AnyValue>(3);
-        m_A = units.convert(rate_vec[0], rate_units);
+        m_A = units.convert(rate_vec[0], m_rate_units);
         m_b = rate_vec[1].asDouble();
         m_Ea_R = units.convertActivationEnergy(rate_vec[2], "K");
     }
 }
 
+void ArrheniusBase::getParameters(AnyMap& node) const
+{
+    getParameters(node, m_rate_units);
+}
+
 void ArrheniusBase::getParameters(AnyMap& node, const Units& rate_units) const
 {
     if (std::isnan(m_A)) {
@@ -92,7 +107,7 @@ void ArrheniusBase::validate(const std::string& equation)
     }
 }
 
-void Arrhenius3::setParameters(const AnyMap& node, const Units& rate_units)
+void Arrhenius3::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     allow_negative_pre_exponential_factor = node.getBool("negative-A", false);
     if (!node.hasKey("rate-constant")) {
@@ -103,13 +118,13 @@ void Arrhenius3::setParameters(const AnyMap& node, const Units& rate_units)
     ArrheniusBase::setParameters(node["rate-constant"], node.units(), rate_units);
 }
 
-void Arrhenius3::getParameters(AnyMap& rateNode, const Units& rate_units) const
+void Arrhenius3::getParameters(AnyMap& rateNode) const
 {
     if (allow_negative_pre_exponential_factor) {
         rateNode["negative-A"] = true;
     }
     AnyMap node;
-    ArrheniusBase::getParameters(node, rate_units);
+    ArrheniusBase::getParameters(node);
     if (!node.empty()) {
         // Arrhenius object is configured
         rateNode["rate-constant"] = std::move(node);
@@ -133,28 +148,34 @@ BlowersMasel3::BlowersMasel3(double A, double b, double Ea0, double w)
 }
 
 void BlowersMasel3::setParameters(
-    const AnyValue& rate, const UnitSystem& units, const Units& rate_units)
+    const AnyValue& rate, const UnitSystem& units, const UnitsVector& rate_units)
 {
     if (rate.empty()) {
         m_A = NAN;
         m_b = NAN;
         m_Ea0_R = NAN;
         m_w_R = NAN;
-    } else if (rate.is<AnyMap>()) {
+        m_order = NAN;
+        m_rate_units = Units(0.);
+        return;
+    }
+
+    if (rate.is<AnyMap>()) {
         ArrheniusBase::setParameters(rate, units, rate_units);
         auto& rate_map = rate.as<AnyMap>();
         m_Ea0_R = units.convertActivationEnergy(rate_map["Ea0"], "K");
         m_w_R = units.convertActivationEnergy(rate_map["w"], "K");
     } else {
+        setRateUnits(rate_units);
         auto& rate_vec = rate.asVector<AnyValue>(4);
-        m_A = units.convert(rate_vec[0], rate_units);
+        m_A = units.convert(rate_vec[0], m_rate_units);
         m_b = rate_vec[1].asDouble();
         m_Ea0_R = units.convertActivationEnergy(rate_vec[2], "K");
         m_w_R = units.convertActivationEnergy(rate_vec[3], "K");
     }
 }
 
-void BlowersMasel3::setParameters(const AnyMap& node, const Units& rate_units)
+void BlowersMasel3::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     allow_negative_pre_exponential_factor = node.getBool("negative-A", false);
     if (!node.hasKey("rate-constant")) {
@@ -164,14 +185,13 @@ void BlowersMasel3::setParameters(const AnyMap& node, const Units& rate_units)
     BlowersMasel3::setParameters(node["rate-constant"], node.units(), rate_units);
 }
 
-void BlowersMasel3::getParameters(AnyMap& rateNode,
-                                     const Units& rate_units) const
+void BlowersMasel3::getParameters(AnyMap& rateNode) const
 {
     if (allow_negative_pre_exponential_factor) {
         rateNode["negative-A"] = true;
     }
     AnyMap node;
-    ArrheniusBase::getParameters(node, rate_units);
+    ArrheniusBase::getParameters(node);
     if (!node.empty()) {
         // object is configured
         node.erase("Ea");
diff --git a/src/kinetics/Falloff.cpp b/src/kinetics/Falloff.cpp
index 1167321486e..6bcef6878c4 100644
--- a/src/kinetics/Falloff.cpp
+++ b/src/kinetics/Falloff.cpp
@@ -57,21 +57,27 @@ void Falloff::getData(vector_fp& c) const
     c.clear();
 }
 
-void Falloff::setParameters(const AnyMap& node, const Units& rate_units)
+void Falloff::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     if (node["type"] == "chemically-activated") {
         m_chemicallyActivated = true;
     }
     allow_negative_pre_exponential_factor = node.getBool("negative-A", false);
     if (node.hasKey("low-P-rate-constant")) {
-        m_lowRate = ArrheniusBase(node["low-P-rate-constant"], node.units(), rate_units);
+        m_lowRate = ArrheniusBase(
+            node["low-P-rate-constant"], node.units(), rate_units);
+    }
+    UnitsVector low_rate_units = rate_units;
+    if (low_rate_units.size()) {
+        low_rate_units.pop_back();
     }
     if (node.hasKey("high-P-rate-constant")) {
-        m_highRate = ArrheniusBase(node["high-P-rate-constant"], node.units(), rate_units);
+        m_highRate = ArrheniusBase(
+            node["high-P-rate-constant"], node.units(), low_rate_units);
     }
 }
 
-void Falloff::getParameters(AnyMap& rateNode, const Units& rate_units) const
+void Falloff::getParameters(AnyMap& rateNode) const
 {
     if (m_chemicallyActivated) {
         rateNode["type"] = "chemically-activated";
@@ -82,12 +88,12 @@ void Falloff::getParameters(AnyMap& rateNode, const Units& rate_units) const
         rateNode["negative-A"] = true;
     }
     AnyMap node;
-    m_lowRate.getParameters(node, rate_units);
+    m_lowRate.getParameters(node);
     if (!node.empty()) {
         rateNode["low-P-rate-constant"] = std::move(node);
     }
     node.clear();
-    m_highRate.getParameters(node, rate_units);
+    m_highRate.getParameters(node);
     if (!node.empty()) {
         rateNode["high-P-rate-constant"] = std::move(node);
     }
@@ -189,7 +195,7 @@ double Troe::F(double pr, const double* work) const
     return pow(10.0, lgf);
 }
 
-void Troe::setParameters(const AnyMap& node, const Units& rate_units)
+void Troe::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     Falloff::setParameters(node, rate_units);
     auto& f = node["Troe"].as<AnyMap>();
@@ -216,6 +222,7 @@ void Troe::getParameters(double* params) const {
 
 void Troe::getParameters(AnyMap& reactionNode) const
 {
+    Falloff::getParameters(reactionNode);
     AnyMap params;
     if (!std::isnan(m_a)) {
         params["A"] = m_a;
@@ -229,12 +236,6 @@ void Troe::getParameters(AnyMap& reactionNode) const
     reactionNode["Troe"] = std::move(params);
 }
 
-void Troe::getParameters(AnyMap& rateNode, const Units& rate_units) const
-{
-    Falloff::getParameters(rateNode, rate_units);
-    getParameters(rateNode);
-}
-
 void SRI::setData(const vector_fp& c)
 {
     if (c.size() != 3 && c.size() != 5) {
@@ -289,7 +290,7 @@ double SRI::F(double pr, const double* work) const
     return pow(*work, xx) * work[1];
 }
 
-void SRI::setParameters(const AnyMap& node, const Units& rate_units)
+void SRI::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     Falloff::setParameters(node, rate_units);
     auto& f = node["SRI"].as<AnyMap>();
@@ -321,6 +322,7 @@ void SRI::getParameters(double* params) const
 
 void SRI::getParameters(AnyMap& reactionNode) const
 {
+    Falloff::getParameters(reactionNode);
     AnyMap params;
     if (!std::isnan(m_a)) {
         params["A"] = m_a;
@@ -335,12 +337,6 @@ void SRI::getParameters(AnyMap& reactionNode) const
     reactionNode["SRI"] = std::move(params);
 }
 
-void SRI::getParameters(AnyMap& rateNode, const Units& rate_units) const
-{
-    Falloff::getParameters(rateNode, rate_units);
-    getParameters(rateNode);
-}
-
 void Tsang::setData(const vector_fp& c)
 {
     if (c.size() != 1 && c.size() != 2) {
@@ -383,7 +379,7 @@ double Tsang::F(double pr, const double* work) const
     return pow(10.0, lgf);
 }
 
-void Tsang::setParameters(const AnyMap& node, const Units& rate_units)
+void Tsang::setParameters(const AnyMap& node, const UnitsVector& rate_units)
 {
     Falloff::setParameters(node, rate_units);
     auto& f = node["Tsang"].as<AnyMap>();
@@ -404,6 +400,7 @@ void Tsang::getParameters(double* params) const {
 
 void Tsang::getParameters(AnyMap& reactionNode) const
 {
+    Falloff::getParameters(reactionNode);
     AnyMap params;
     if (!std::isnan(m_a)) {
         params["A"] = m_a;
@@ -413,10 +410,4 @@ void Tsang::getParameters(AnyMap& reactionNode) const
     reactionNode["Tsang"] = std::move(params);
 }
 
-void Tsang::getParameters(AnyMap& rateNode, const Units& rate_units) const
-{
-    Falloff::getParameters(rateNode, rate_units);
-    getParameters(rateNode);
-}
-
 }
diff --git a/src/kinetics/Reaction.cpp b/src/kinetics/Reaction.cpp
index f589b1183bd..01e6663a557 100644
--- a/src/kinetics/Reaction.cpp
+++ b/src/kinetics/Reaction.cpp
@@ -159,7 +159,7 @@ void Reaction::getParameters(AnyMap& reactionNode) const
     }
 
     if (m_rate) {
-        reactionNode.update(m_rate->parameters(rate_units));
+        reactionNode.update(m_rate->parameters());
     }
 }
 
@@ -268,11 +268,6 @@ void Reaction::calculateRateCoeffUnits(const Kinetics& kin)
             rate_units *= phase.standardConcentrationUnits().pow(-stoich.second);
         }
     }
-
-    if (m_rate) {
-        // Ensure that reaction rate object is updated
-        m_rate->setUnits(rate_units);
-    }
 }
 
 UnitsVector Reaction::calculateRateCoeffUnits3(const Kinetics& kin)
diff --git a/src/kinetics/ReactionRate.cpp b/src/kinetics/ReactionRate.cpp
index 14a08910472..f7a596bb805 100644
--- a/src/kinetics/ReactionRate.cpp
+++ b/src/kinetics/ReactionRate.cpp
@@ -16,9 +16,9 @@ PlogRate::PlogRate(const std::multimap<double, Arrhenius>& rates)
 {
 }
 
-PlogRate::PlogRate(const AnyMap& node, const Units& rate_units)
+PlogRate::PlogRate(const AnyMap& node, const UnitsVector& units)
 {
-    setParameters(node, rate_units);
+    setParameters(node, units);
 }
 
 unique_ptr<MultiRateBase> PlogRate::newMultiRate() const
@@ -26,11 +26,12 @@ unique_ptr<MultiRateBase> PlogRate::newMultiRate() const
     return unique_ptr<MultiRateBase>(new MultiBulkRate<PlogRate, PlogData>);
 }
 
-void PlogRate::setParameters(const AnyMap& node, const Units& rate_units)
+void PlogRate::setParameters(const AnyMap& node, const UnitsVector& units)
 {
     // @TODO  implementation of Plog::setParameters should be transferred here
     //     when the Plog class is removed from RxnRates.h after Cantera 2.6
-    ReactionRateBase::setParameters(node, rate_units);
+    ReactionRateBase::setParameters(node, units);
+    auto rate_units = Units::product(units);
     if (!node.hasKey("rate-constants")) {
         Plog::setParameters(std::vector<AnyMap> (), node.units(), rate_units);
         return;
@@ -40,11 +41,11 @@ void PlogRate::setParameters(const AnyMap& node, const Units& rate_units)
                         node.units(), rate_units);
 }
 
-void PlogRate::getParameters(AnyMap& rateNode, const Units& rate_units) const
+void PlogRate::getParameters(AnyMap& rateNode) const
 {
     // @TODO  implementation of Plog::getParameters should be transferred here
     //     when the Plog class is removed from RxnRates.h after Cantera 2.6
-    Plog::getParameters(rateNode, rate_units);
+    Plog::getParameters(rateNode);
     rateNode["type"] = type();
 }
 
@@ -54,9 +55,9 @@ ChebyshevRate3::ChebyshevRate3(double Tmin, double Tmax, double Pmin, double Pma
 {
 }
 
-ChebyshevRate3::ChebyshevRate3(const AnyMap& node, const Units& rate_units)
+ChebyshevRate3::ChebyshevRate3(const AnyMap& node, const UnitsVector& units)
 {
-    setParameters(node, rate_units);
+    setParameters(node, units);
 }
 
 unique_ptr<MultiRateBase> ChebyshevRate3::newMultiRate() const
@@ -65,24 +66,24 @@ unique_ptr<MultiRateBase> ChebyshevRate3::newMultiRate() const
         new MultiBulkRate<ChebyshevRate3, ChebyshevData>);
 }
 
-void ChebyshevRate3::setParameters(const AnyMap& node, const Units& rate_units)
+void ChebyshevRate3::setParameters(const AnyMap& node, const UnitsVector& units)
 {
-    ReactionRateBase::setParameters(node, rate_units);
+    ReactionRateBase::setParameters(node, units);
+    m_rate_units = Units::product(units);
     if (!node.hasKey("data")) {
-        Chebyshev::setParameters(AnyMap(), node.units(), rate_units);
+        Chebyshev::setParameters(AnyMap(), node.units(), m_rate_units);
         return;
     }
     // @TODO  implementation of Chebyshev::setParameters should be transferred here
     //     when the Chebyshev class is removed from RxnRates.h after Cantera 2.6
-    Chebyshev::setParameters(node, node.units(), rate_units);
+    Chebyshev::setParameters(node, node.units(), m_rate_units);
 }
 
-void ChebyshevRate3::getParameters(AnyMap& rateNode,
-                                   const Units& rate_units) const
+void ChebyshevRate3::getParameters(AnyMap& rateNode) const
 {
     // @TODO  implementation of Chebyshev::getParameters should be transferred here
     //     when the Chebyshev class is removed from RxnRates.h after Cantera 2.6
-    Chebyshev::getParameters(rateNode, rate_units);
+    Chebyshev::getParameters(rateNode, m_rate_units);
     rateNode["type"] = type();
 }
 
diff --git a/src/kinetics/RxnRates.cpp b/src/kinetics/RxnRates.cpp
index 10788f12500..0d4b9ea4709 100644
--- a/src/kinetics/RxnRates.cpp
+++ b/src/kinetics/RxnRates.cpp
@@ -35,7 +35,9 @@ Arrhenius2::Arrhenius2(const AnyValue& rate,
 void Arrhenius2::setParameters(const AnyValue& rate,
                                const UnitSystem& units, const Units& rate_units)
 {
-    ArrheniusBase::setParameters(rate, units, rate_units);
+    UnitsVector units_vector;
+    units_vector.emplace_back(rate_units, 1.);
+    ArrheniusBase::setParameters(rate, units, units_vector);
     if (m_A <= 0.0) {
         m_logA = -1.0E300;
     } else {
@@ -157,7 +159,7 @@ void Plog::getParameters(AnyMap& rateNode, const Units& rate_units) const
     for (const auto& r : getRates()) {
         AnyMap rateNode_;
         rateNode_["P"].setQuantity(r.first, "Pa");
-        r.second.getParameters(rateNode_, rate_units);
+        r.second.getParameters(rateNode_);
         rateList.push_back(std::move(rateNode_));
     }
     rateNode["rate-constants"] = std::move(rateList);