diff --git a/src/Responses/Chat/CreateResponseMessage.php b/src/Responses/Chat/CreateResponseMessage.php
index 48ae6293..bc2954bc 100644
--- a/src/Responses/Chat/CreateResponseMessage.php
+++ b/src/Responses/Chat/CreateResponseMessage.php
@@ -14,6 +14,7 @@ private function __construct(
         public readonly ?string $content,
         public readonly array $toolCalls,
         public readonly ?CreateResponseFunctionCall $functionCall,
+        public readonly ?string $reasoningContent,
     ) {}
 
     /**
@@ -30,6 +31,7 @@ public static function from(array $attributes): self
             $attributes['content'] ?? null,
             $toolCalls,
             isset($attributes['function_call']) ? CreateResponseFunctionCall::from($attributes['function_call']) : null,
+            $attributes['reasoning_content'] ?? null,
         );
     }
 
@@ -51,6 +53,10 @@ public function toArray(): array
             $data['tool_calls'] = array_map(fn (CreateResponseToolCall $toolCall): array => $toolCall->toArray(), $this->toolCalls);
         }
 
+        if ($this->reasoningContent) {
+            $data['reasoning_content'] = $this->reasoningContent;
+        }
+
         return $data;
     }
 }