diff --git a/lib/src/main/java/com/knuddels/jtokkit/AbstractEncodingRegistry.java b/lib/src/main/java/com/knuddels/jtokkit/AbstractEncodingRegistry.java
index 531c228..0159e56 100644
--- a/lib/src/main/java/com/knuddels/jtokkit/AbstractEncodingRegistry.java
+++ b/lib/src/main/java/com/knuddels/jtokkit/AbstractEncodingRegistry.java
@@ -36,6 +36,10 @@ public Optional<Encoding> getEncodingForModel(final String modelName) {
             return Optional.of(getEncodingForModel(ModelType.GPT_4O));
         }
 
+        if (modelName.startsWith(ModelType.O1.getName())) {
+            return Optional.of(getEncodingForModel(ModelType.O1));
+        }
+
         if (modelName.startsWith(ModelType.GPT_4_32K.getName())) {
             return Optional.of(getEncodingForModel(ModelType.GPT_4_32K));
         }
diff --git a/lib/src/main/java/com/knuddels/jtokkit/api/ModelType.java b/lib/src/main/java/com/knuddels/jtokkit/api/ModelType.java
index d2623da..5c1fe4f 100644
--- a/lib/src/main/java/com/knuddels/jtokkit/api/ModelType.java
+++ b/lib/src/main/java/com/knuddels/jtokkit/api/ModelType.java
@@ -15,6 +15,8 @@ public enum ModelType {
     GPT_4_TURBO("gpt-4-turbo", EncodingType.CL100K_BASE, 128000),
     GPT_3_5_TURBO("gpt-3.5-turbo", EncodingType.CL100K_BASE, 16385),
     GPT_3_5_TURBO_16K("gpt-3.5-turbo-16k", EncodingType.CL100K_BASE, 16385),
+    O1("o1", EncodingType.O200K_BASE, 200000),
+    O1_MINI("o1-mini", EncodingType.O200K_BASE, 128000),
 
     // text
     TEXT_DAVINCI_003("text-davinci-003", EncodingType.P50K_BASE, 4097),
diff --git a/lib/src/test/java/com/knuddels/jtokkit/BaseEncodingRegistryTest.java b/lib/src/test/java/com/knuddels/jtokkit/BaseEncodingRegistryTest.java
index d14afa9..6a0af6c 100644
--- a/lib/src/test/java/com/knuddels/jtokkit/BaseEncodingRegistryTest.java
+++ b/lib/src/test/java/com/knuddels/jtokkit/BaseEncodingRegistryTest.java
@@ -102,6 +102,27 @@ void getEncodingForModelByPrefixReturnsCorrectEncodingForGpt4oMini() {
         assertEquals(encoding.get().getName(), ModelType.GPT_4O_MINI.getEncodingType().getName());
     }
 
+    @Test
+    void getEncodingForModelByPrefixReturnsCorrectEncodingForO1Mini() {
+        var encoding = registry.getEncodingForModel("o1-mini-2024-09-12");
+        assertTrue(encoding.isPresent());
+        assertEquals(encoding.get().getName(), ModelType.O1_MINI.getEncodingType().getName());
+    }
+
+    @Test
+    void getEncodingForModelByPrefixReturnsCorrectEncodingForO1() {
+        var encoding = registry.getEncodingForModel("o1-2024-12-17");
+        assertTrue(encoding.isPresent());
+        assertEquals(encoding.get().getName(), ModelType.O1.getEncodingType().getName());
+    }
+
+    @Test
+    void getEncodingForModelByPrefixReturnsCorrectEncodingForO1Preview() {
+        var encoding = registry.getEncodingForModel("o1-preview-2024-09-12");
+        assertTrue(encoding.isPresent());
+        assertEquals(encoding.get().getName(), ModelType.O1.getEncodingType().getName());
+    }
+
     @Test
     void getEncodingForModelByPrefixReturnsCorrectEncodingForGpt4Turbo() {
         var encoding = registry.getEncodingForModel("gpt-4-turbo-123");