diff --git a/async-openai/src/types/chat.rs b/async-openai/src/types/chat.rs
index d9373db6..c2b28618 100644
--- a/async-openai/src/types/chat.rs
+++ b/async-openai/src/types/chat.rs
@@ -436,6 +436,10 @@ pub struct ChatCompletionResponseMessage {
     #[deprecated]
     pub function_call: Option<FunctionCall>,
 
+    /// OpenRouter uses reasoning field to return thinking content when reasoning parser is enabled
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reasoning: Option<String>,
+
     /// If the audio output modality is requested, this object contains data about the audio response from the model. [Learn more](https://platform.openai.com/docs/guides/audio).
     #[serde(skip_serializing_if = "Option::is_none")]
     pub audio: Option<ChatCompletionResponseMessageAudio>,
@@ -494,6 +498,8 @@ pub enum ResponseFormat {
     JsonSchema {
         json_schema: ResponseFormatJsonSchema,
     },
+    /// The type of response format being defined: grammar
+    Grammar { grammar: String },
 }
 
 #[derive(Debug, Deserialize, Serialize, Clone, PartialEq)]
@@ -1006,6 +1012,10 @@ pub struct ChatCompletionStreamResponseDelta {
     #[deprecated]
     pub function_call: Option<FunctionCallStream>,
 
+    /// OpenRouter uses reasoning field to return thinking content when reasoning parser is enabled
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reasoning: Option<String>,
+
     pub tool_calls: Option<Vec<ChatCompletionMessageToolCallChunk>>,
     /// The role of the author of this message.
     pub role: Option<Role>,