diff --git a/rmgpy/molecule/molecule.pxd b/rmgpy/molecule/molecule.pxd
index 04aaefc3d2..0df48e717c 100644
--- a/rmgpy/molecule/molecule.pxd
+++ b/rmgpy/molecule/molecule.pxd
@@ -133,6 +133,10 @@ cdef class Molecule(Graph):
     cdef str _inchi
     cdef str _smiles
 
+    cpdef bint is_equal(self, Molecule other)
+
+    cpdef bint is_same(self, other)
+
     cpdef addAtom(self, Atom atom)
 
     cpdef addBond(self, Bond bond)
diff --git a/rmgpy/molecule/molecule.py b/rmgpy/molecule/molecule.py
index bd0a2881db..04c993409d 100644
--- a/rmgpy/molecule/molecule.py
+++ b/rmgpy/molecule/molecule.py
@@ -757,6 +757,15 @@ def is_equal(self,other):
         else:
             return self.isIsomorphic(other)   
 
+    def is_same(self, other):
+        """
+        Chemical identity comparison via InChI strings.
+        """
+        if self.multiplicity == other.multiplicity and self.InChI == other.InChI:
+            return True
+        else:
+            return False
+
     def __str__(self):
         """
         Return a human-readable string representation of the object.