diff --git a/crates/lingua/src/processing/transform.rs b/crates/lingua/src/processing/transform.rs
index 6d36ffa6..40f0abc8 100644
--- a/crates/lingua/src/processing/transform.rs
+++ b/crates/lingua/src/processing/transform.rs
@@ -1188,6 +1188,74 @@ mod tests {
         assert!(output.get("top_p").is_none(), "Should not have top_p");
     }
 
+    #[test]
+    #[cfg(all(feature = "openai", feature = "google"))]
+    fn test_google_top_k_openai_model_drops_top_k_for_chat_completions() {
+        let payload = json!({
+            "contents": [{
+                "role": "user",
+                "parts": [{"text": "Write a short sentence about API gateways."}]
+            }],
+            "generationConfig": {
+                "topK": 1,
+                "maxOutputTokens": 1024
+            }
+        });
+        let input = to_bytes(&payload);
+
+        let result =
+            transform_request(input, ProviderFormat::ChatCompletions, Some("gpt-5-nano")).unwrap();
+
+        let output: Value = crate::serde_json::from_slice(result.as_bytes()).unwrap();
+        assert_eq!(result.source_format(), Some(ProviderFormat::Google));
+        assert_eq!(
+            output.get("model").and_then(Value::as_str),
+            Some("gpt-5-nano")
+        );
+        assert!(
+            output.get("top_k").is_none(),
+            "OpenAI Chat Completions should not receive top_k"
+        );
+        assert_eq!(
+            output.get("max_completion_tokens").and_then(Value::as_i64),
+            Some(1024)
+        );
+    }
+
+    #[test]
+    #[cfg(all(feature = "openai", feature = "google"))]
+    fn test_google_top_k_openai_model_drops_top_k_for_responses() {
+        let payload = json!({
+            "contents": [{
+                "role": "user",
+                "parts": [{"text": "Write a short sentence about API gateways."}]
+            }],
+            "generationConfig": {
+                "topK": 1,
+                "maxOutputTokens": 1024
+            }
+        });
+        let input = to_bytes(&payload);
+
+        let result =
+            transform_request(input, ProviderFormat::Responses, Some("gpt-5-nano")).unwrap();
+
+        let output: Value = crate::serde_json::from_slice(result.as_bytes()).unwrap();
+        assert_eq!(result.source_format(), Some(ProviderFormat::Google));
+        assert_eq!(
+            output.get("model").and_then(Value::as_str),
+            Some("gpt-5-nano")
+        );
+        assert!(
+            output.get("top_k").is_none(),
+            "OpenAI Responses should not receive top_k"
+        );
+        assert_eq!(
+            output.get("max_output_tokens").and_then(Value::as_i64),
+            Some(1024)
+        );
+    }
+
     #[test]
     #[cfg(feature = "openai")]
     fn test_non_reasoning_model_still_passthroughs() {
diff --git a/payloads/cases/params.ts b/payloads/cases/params.ts
index 2a1af361..66726065 100644
--- a/payloads/cases/params.ts
+++ b/payloads/cases/params.ts
@@ -1505,6 +1505,25 @@ export const paramsCases: TestCaseCollection = {
     bedrock: null,
   },
 
+  googleOpenAIModelTopKParam: {
+    "chat-completions": null,
+    responses: null,
+    anthropic: null,
+    google: {
+      contents: [
+        {
+          role: "user",
+          parts: [{ text: "Write a short sentence about API gateways." }],
+        },
+      ],
+      generationConfig: {
+        topK: 1,
+        maxOutputTokens: 1024,
+      },
+    },
+    bedrock: null,
+  },
+
   streamParam: {
     "chat-completions": null,
     responses: null,
diff --git a/payloads/scripts/transforms/__snapshots__/transforms.test.ts.snap b/payloads/scripts/transforms/__snapshots__/transforms.test.ts.snap
index e8b426a6..a0308b1a 100644
--- a/payloads/scripts/transforms/__snapshots__/transforms.test.ts.snap
+++ b/payloads/scripts/transforms/__snapshots__/transforms.test.ts.snap
@@ -14997,6 +14997,46 @@ What maximum token limit would you like to set?",
 }
 `;
 
+exports[`google → anthropic > googleOpenAIModelTopKParam > request 1`] = `
+{
+  "max_tokens": 1024,
+  "messages": [
+    {
+      "content": "Write a short sentence about API gateways.",
+      "role": "user",
+    },
+  ],
+  "model": "claude-sonnet-4-5-20250929",
+  "top_k": 1,
+}
+`;
+
+exports[`google → anthropic > googleOpenAIModelTopKParam > response 1`] = `
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "An API gateway acts as a single entry point that routes client requests to appropriate backend services while handling cross-cutting concerns like authentication, rate limiting, and logging.",
+          },
+        ],
+        "role": "model",
+      },
+      "finishReason": "STOP",
+      "index": 0,
+    },
+  ],
+  "modelVersion": "claude-sonnet-4-5-20250929",
+  "usageMetadata": {
+    "cachedContentTokenCount": 0,
+    "candidatesTokenCount": 35,
+    "promptTokenCount": 17,
+    "totalTokenCount": 52,
+  },
+}
+`;
+
 exports[`google → anthropic > googleResponseSchemaPropertyOrderingParam > request 1`] = `
 {
   "max_tokens": 128,
@@ -17365,6 +17405,46 @@ Would you like me to set max_tokens to 1024 now, or provide a different value? I
 }
 `;
 
+exports[`google → chat-completions > googleOpenAIModelTopKParam > request 1`] = `
+{
+  "max_completion_tokens": 1024,
+  "messages": [
+    {
+      "content": "Write a short sentence about API gateways.",
+      "role": "user",
+    },
+  ],
+  "model": "gpt-5-nano",
+}
+`;
+
+exports[`google → chat-completions > googleOpenAIModelTopKParam > response 1`] = `
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "An API gateway sits between clients and backend services, routing requests and enforcing security.",
+          },
+        ],
+        "role": "model",
+      },
+      "finishReason": "STOP",
+      "index": 0,
+    },
+  ],
+  "modelVersion": "gpt-5-nano-2025-08-07",
+  "usageMetadata": {
+    "cachedContentTokenCount": 0,
+    "candidatesTokenCount": 25,
+    "promptTokenCount": 14,
+    "thoughtsTokenCount": 256,
+    "totalTokenCount": 295,
+  },
+}
+`;
+
 exports[`google → chat-completions > googleResponseSchemaPropertyOrderingParam > request 1`] = `
 {
   "max_completion_tokens": 128,
@@ -19608,6 +19688,59 @@ exports[`google → responses > exclusiveMinimumToolParam > response 1`] = `
 }
 `;
 
+exports[`google → responses > googleOpenAIModelTopKParam > request 1`] = `
+{
+  "input": [
+    {
+      "content": "Write a short sentence about API gateways.",
+      "role": "user",
+    },
+  ],
+  "max_output_tokens": 1024,
+  "model": "gpt-5-nano",
+}
+`;
+
+exports[`google → responses > googleOpenAIModelTopKParam > response 1`] = `
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "",
+            "thought": true,
+          },
+        ],
+        "role": "model",
+      },
+      "finishReason": "STOP",
+      "index": 0,
+    },
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "An API gateway acts as a single entry point that handles authentication, rate limiting, and routing for backend services.",
+          },
+        ],
+        "role": "model",
+      },
+      "finishReason": "STOP",
+      "index": 1,
+    },
+  ],
+  "modelVersion": "gpt-5-nano-2025-08-07",
+  "usageMetadata": {
+    "cachedContentTokenCount": 0,
+    "candidatesTokenCount": 62,
+    "promptTokenCount": 14,
+    "thoughtsTokenCount": 192,
+    "totalTokenCount": 268,
+  },
+}
+`;
+
 exports[`google → responses > googleResponseSchemaPropertyOrderingParam > request 1`] = `
 {
   "input": [
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-request.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-request.json
new file mode 100644
index 00000000..4d474e80
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-request.json
@@ -0,0 +1,32 @@
+{
+  "contents": [
+    {
+      "role": "user",
+      "parts": [
+        {
+          "text": "Write a short sentence about API gateways."
+        }
+      ]
+    },
+    {
+      "role": "model",
+      "parts": [
+        {
+          "text": "An API gateway acts as a single entry point for managing and securing access to your APIs."
+        }
+      ]
+    },
+    {
+      "role": "user",
+      "parts": [
+        {
+          "text": "What should I do next?"
+        }
+      ]
+    }
+  ],
+  "generationConfig": {
+    "topK": 1,
+    "maxOutputTokens": 1024
+  }
+}
\ No newline at end of file
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response-streaming.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response-streaming.json
new file mode 100644
index 00000000..d56780e1
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response-streaming.json
@@ -0,0 +1,63 @@
+[
+  {
+    "candidates": [
+      {
+        "content": {
+          "parts": [
+            {
+              "text": "That's a great question, and \"what you should do next\" really depends on your goal!\n\nTo help me guide you"
+            }
+          ],
+          "role": "model"
+        },
+        "index": 0
+      }
+    ],
+    "usageMetadata": {
+      "promptTokenCount": 35,
+      "candidatesTokenCount": 27,
+      "totalTokenCount": 1043,
+      "promptTokensDetails": [
+        {
+          "modality": "TEXT",
+          "tokenCount": 35
+        }
+      ],
+      "thoughtsTokenCount": 981,
+      "serviceTier": "standard"
+    },
+    "modelVersion": "gemini-2.5-flash",
+    "responseId": "3x8Cavq-EomD-8YPoO7ukQw"
+  },
+  {
+    "candidates": [
+      {
+        "content": {
+          "parts": [
+            {
+              "text": " better, could you tell me:\n\n*   **Are"
+            }
+          ],
+          "role": "model"
+        },
+        "finishReason": "MAX_TOKENS",
+        "index": 0
+      }
+    ],
+    "usageMetadata": {
+      "promptTokenCount": 35,
+      "candidatesTokenCount": 39,
+      "totalTokenCount": 1055,
+      "promptTokensDetails": [
+        {
+          "modality": "TEXT",
+          "tokenCount": 35
+        }
+      ],
+      "thoughtsTokenCount": 981,
+      "serviceTier": "standard"
+    },
+    "modelVersion": "gemini-2.5-flash",
+    "responseId": "3x8Cavq-EomD-8YPoO7ukQw"
+  }
+]
\ No newline at end of file
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response.json
new file mode 100644
index 00000000..1fdf4114
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/followup-response.json
@@ -0,0 +1,31 @@
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "That depends entirely on what your goals are! Since you just got a definition, here are a few paths you could take:\n\n1.  **If you want to learn more about API Gateways:**\n    *   **Dive into their features:** Research common functionalities like rate limiting, authentication/authorization"
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "MAX_TOKENS",
+      "index": 0
+    }
+  ],
+  "usageMetadata": {
+    "promptTokenCount": 35,
+    "candidatesTokenCount": 61,
+    "totalTokenCount": 1055,
+    "promptTokensDetails": [
+      {
+        "modality": "TEXT",
+        "tokenCount": 35
+      }
+    ],
+    "thoughtsTokenCount": 959,
+    "serviceTier": "standard"
+  },
+  "modelVersion": "gemini-2.5-flash",
+  "responseId": "3x8CauzREryt-8YPg7jH8A0"
+}
\ No newline at end of file
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/request.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/request.json
new file mode 100644
index 00000000..17c74b13
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/request.json
@@ -0,0 +1,16 @@
+{
+  "contents": [
+    {
+      "role": "user",
+      "parts": [
+        {
+          "text": "Write a short sentence about API gateways."
+        }
+      ]
+    }
+  ],
+  "generationConfig": {
+    "topK": 1,
+    "maxOutputTokens": 1024
+  }
+}
\ No newline at end of file
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/response-streaming.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/response-streaming.json
new file mode 100644
index 00000000..35fb2644
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/response-streaming.json
@@ -0,0 +1,33 @@
+[
+  {
+    "candidates": [
+      {
+        "content": {
+          "parts": [
+            {
+              "text": "API gateways serve as a centralized entry point for managing and securing API requests."
+            }
+          ],
+          "role": "model"
+        },
+        "finishReason": "STOP",
+        "index": 0
+      }
+    ],
+    "usageMetadata": {
+      "promptTokenCount": 9,
+      "candidatesTokenCount": 15,
+      "totalTokenCount": 508,
+      "promptTokensDetails": [
+        {
+          "modality": "TEXT",
+          "tokenCount": 9
+        }
+      ],
+      "thoughtsTokenCount": 484,
+      "serviceTier": "standard"
+    },
+    "modelVersion": "gemini-2.5-flash",
+    "responseId": "2h8CasjSJra9sOIP-J-VqAM"
+  }
+]
\ No newline at end of file
diff --git a/payloads/snapshots/googleOpenAIModelTopKParam/google/response.json b/payloads/snapshots/googleOpenAIModelTopKParam/google/response.json
new file mode 100644
index 00000000..e04749b6
--- /dev/null
+++ b/payloads/snapshots/googleOpenAIModelTopKParam/google/response.json
@@ -0,0 +1,31 @@
+{
+  "candidates": [
+    {
+      "content": {
+        "parts": [
+          {
+            "text": "An API gateway acts as a single entry point for managing and securing access to your APIs."
+          }
+        ],
+        "role": "model"
+      },
+      "finishReason": "STOP",
+      "index": 0
+    }
+  ],
+  "usageMetadata": {
+    "promptTokenCount": 9,
+    "candidatesTokenCount": 18,
+    "totalTokenCount": 862,
+    "promptTokensDetails": [
+      {
+        "modality": "TEXT",
+        "tokenCount": 9
+      }
+    ],
+    "thoughtsTokenCount": 835,
+    "serviceTier": "standard"
+  },
+  "modelVersion": "gemini-2.5-flash",
+  "responseId": "2h8CatPEJomY-8YP-qrAsA0"
+}
\ No newline at end of file
diff --git a/payloads/transforms/google_to_anthropic/googleOpenAIModelTopKParam.json b/payloads/transforms/google_to_anthropic/googleOpenAIModelTopKParam.json
new file mode 100644
index 00000000..f4d838a0
--- /dev/null
+++ b/payloads/transforms/google_to_anthropic/googleOpenAIModelTopKParam.json
@@ -0,0 +1,27 @@
+{
+  "model": "claude-sonnet-4-5-20250929",
+  "id": "msg_01HaceWFZKkAcRjrJxZGu4Ux",
+  "type": "message",
+  "role": "assistant",
+  "content": [
+    {
+      "type": "text",
+      "text": "An API gateway acts as a single entry point that routes client requests to appropriate backend services while handling cross-cutting concerns like authentication, rate limiting, and logging."
+    }
+  ],
+  "stop_reason": "end_turn",
+  "stop_sequence": null,
+  "stop_details": null,
+  "usage": {
+    "input_tokens": 17,
+    "cache_creation_input_tokens": 0,
+    "cache_read_input_tokens": 0,
+    "cache_creation": {
+      "ephemeral_5m_input_tokens": 0,
+      "ephemeral_1h_input_tokens": 0
+    },
+    "output_tokens": 35,
+    "service_tier": "standard",
+    "inference_geo": "not_available"
+  }
+}
\ No newline at end of file
diff --git a/payloads/transforms/google_to_chat-completions/googleOpenAIModelTopKParam.json b/payloads/transforms/google_to_chat-completions/googleOpenAIModelTopKParam.json
new file mode 100644
index 00000000..48a0e086
--- /dev/null
+++ b/payloads/transforms/google_to_chat-completions/googleOpenAIModelTopKParam.json
@@ -0,0 +1,35 @@
+{
+  "id": "chatcmpl-DePf3UW2reZN7Bj9tefiRJf3P2m3o",
+  "object": "chat.completion",
+  "created": 1778524133,
+  "model": "gpt-5-nano-2025-08-07",
+  "choices": [
+    {
+      "index": 0,
+      "message": {
+        "role": "assistant",
+        "content": "An API gateway sits between clients and backend services, routing requests and enforcing security.",
+        "refusal": null,
+        "annotations": []
+      },
+      "finish_reason": "stop"
+    }
+  ],
+  "usage": {
+    "prompt_tokens": 14,
+    "completion_tokens": 281,
+    "total_tokens": 295,
+    "prompt_tokens_details": {
+      "cached_tokens": 0,
+      "audio_tokens": 0
+    },
+    "completion_tokens_details": {
+      "reasoning_tokens": 256,
+      "audio_tokens": 0,
+      "accepted_prediction_tokens": 0,
+      "rejected_prediction_tokens": 0
+    }
+  },
+  "service_tier": "default",
+  "system_fingerprint": null
+}
\ No newline at end of file
diff --git a/payloads/transforms/google_to_responses/googleOpenAIModelTopKParam.json b/payloads/transforms/google_to_responses/googleOpenAIModelTopKParam.json
new file mode 100644
index 00000000..3971870f
--- /dev/null
+++ b/payloads/transforms/google_to_responses/googleOpenAIModelTopKParam.json
@@ -0,0 +1,78 @@
+{
+  "id": "resp_071751ea08988f74006a021fe649a4819cbc1c52ace5d640dd",
+  "object": "response",
+  "created_at": 1778524134,
+  "status": "completed",
+  "background": false,
+  "billing": {
+    "payer": "developer"
+  },
+  "completed_at": 1778524138,
+  "error": null,
+  "frequency_penalty": 0,
+  "incomplete_details": null,
+  "instructions": null,
+  "max_output_tokens": 1024,
+  "max_tool_calls": null,
+  "model": "gpt-5-nano-2025-08-07",
+  "moderation": null,
+  "output": [
+    {
+      "id": "rs_071751ea08988f74006a021fe8e118819cb6da5f875d4eda07",
+      "type": "reasoning",
+      "summary": []
+    },
+    {
+      "id": "msg_071751ea08988f74006a021fea1754819caf0df8e4c787f577",
+      "type": "message",
+      "status": "completed",
+      "content": [
+        {
+          "type": "output_text",
+          "annotations": [],
+          "logprobs": [],
+          "text": "An API gateway acts as a single entry point that handles authentication, rate limiting, and routing for backend services."
+        }
+      ],
+      "role": "assistant"
+    }
+  ],
+  "parallel_tool_calls": true,
+  "presence_penalty": 0,
+  "previous_response_id": null,
+  "prompt_cache_key": null,
+  "prompt_cache_retention": "in_memory",
+  "reasoning": {
+    "effort": "medium",
+    "summary": null
+  },
+  "safety_identifier": null,
+  "service_tier": "default",
+  "store": true,
+  "temperature": 1,
+  "text": {
+    "format": {
+      "type": "text"
+    },
+    "verbosity": "medium"
+  },
+  "tool_choice": "auto",
+  "tools": [],
+  "top_logprobs": 0,
+  "top_p": 1,
+  "truncation": "disabled",
+  "usage": {
+    "input_tokens": 14,
+    "input_tokens_details": {
+      "cached_tokens": 0
+    },
+    "output_tokens": 254,
+    "output_tokens_details": {
+      "reasoning_tokens": 192
+    },
+    "total_tokens": 268
+  },
+  "user": null,
+  "metadata": {},
+  "output_text": "An API gateway acts as a single entry point that handles authentication, rate limiting, and routing for backend services."
+}
\ No newline at end of file