diff --git a/src/providers/openai.rs b/src/providers/openai.rs
index 08d26053..ad9b74cf 100644
--- a/src/providers/openai.rs
+++ b/src/providers/openai.rs
@@ -159,10 +159,10 @@ impl super::Provider for OpenAIProvider {
             body["temperature"] = serde_json::json!(temp);
         }
         
-        // Newer models (gpt-5, o1) prefer max_completion_tokens
+        // Newer models (gpt-5, o1) in Responses API use max_output_tokens
         if let Some(max_tokens) = request.max_tokens {
             if request.model.contains("gpt-5") || request.model.starts_with("o1-") || request.model.starts_with("o3-") {
-                body["max_completion_tokens"] = serde_json::json!(max_tokens);
+                body["max_output_tokens"] = serde_json::json!(max_tokens);
             } else {
                 body["max_tokens"] = serde_json::json!(max_tokens);
             }
@@ -423,10 +423,10 @@ impl super::Provider for OpenAIProvider {
             body["temperature"] = serde_json::json!(temp);
         }
         
-        // Newer models (gpt-5, o1) prefer max_completion_tokens
+        // Newer models (gpt-5, o1) in Responses API use max_output_tokens
         if let Some(max_tokens) = request.max_tokens {
             if request.model.contains("gpt-5") || request.model.starts_with("o1-") || request.model.starts_with("o3-") {
-                body["max_completion_tokens"] = serde_json::json!(max_tokens);
+                body["max_output_tokens"] = serde_json::json!(max_tokens);
             } else {
                 body["max_tokens"] = serde_json::json!(max_tokens);
             }