diff --git a/python/packages/autogen-core/src/autogen_core/models/_model_client.py b/python/packages/autogen-core/src/autogen_core/models/_model_client.py
index 7c8519ddf..1c1abaea1 100644
--- a/python/packages/autogen-core/src/autogen_core/models/_model_client.py
+++ b/python/packages/autogen-core/src/autogen_core/models/_model_client.py
@@ -31,6 +31,7 @@ class ModelFamily:
     GEMINI_1_5_PRO = "gemini-1.5-pro"
     GEMINI_2_0_FLASH = "gemini-2.0-flash"
     GEMINI_2_5_PRO = "gemini-2.5-pro"
+    GEMINI_2_5_FLASH = "gemini-2.5-flash"
     CLAUDE_3_HAIKU = "claude-3-haiku"
     CLAUDE_3_SONNET = "claude-3-sonnet"
     CLAUDE_3_OPUS = "claude-3-opus"
@@ -64,6 +65,7 @@ class ModelFamily:
         "gemini-1.5-pro",
         "gemini-2.0-flash",
         "gemini-2.5-pro",
+        "gemini-2.5-flash"
         # anthropic_models
         "claude-3-haiku",
         "claude-3-sonnet",
@@ -107,6 +109,7 @@ class ModelFamily:
             ModelFamily.GEMINI_1_5_PRO,
             ModelFamily.GEMINI_2_0_FLASH,
             ModelFamily.GEMINI_2_5_PRO,
+            ModelFamily.GEMINI_2_5_FLASH,
         )
 
     @staticmethod
diff --git a/python/packages/autogen-ext/src/autogen_ext/models/openai/_model_info.py b/python/packages/autogen-ext/src/autogen_ext/models/openai/_model_info.py
index c5b8b0495..4be15ae08 100644
--- a/python/packages/autogen-ext/src/autogen_ext/models/openai/_model_info.py
+++ b/python/packages/autogen-ext/src/autogen_ext/models/openai/_model_info.py
@@ -308,6 +308,14 @@ _MODEL_INFO: Dict[str, ModelInfo] = {
         "structured_output": True,
         "multiple_system_messages": False,
     },
+    "gemini-2.5-flash-preview-05-20": {
+        "vision": True,
+        "function_calling": True,
+        "json_output": True,
+        "family": ModelFamily.GEMINI_2_5_FLASH,
+        "structured_output": True,
+        "multiple_system_messages": False,
+    },
     "claude-3-haiku-20240307": {
         "vision": True,
         "function_calling": True,
@@ -422,6 +430,7 @@ _MODEL_TOKEN_LIMITS: Dict[str, int] = {
     "gemini-2.0-flash": 1048576,
     "gemini-2.0-flash-lite-preview-02-05": 1048576,
     "gemini-2.5-pro-preview-03-25": 2097152,
+    "gemini-2.5-flash-preview-05-20": 1048576,
     "claude-3-haiku-20240307": 50000,
     "claude-3-sonnet-20240229": 40000,
     "claude-3-opus-20240229": 20000,