diff --git a/chatcompletion.go b/chatcompletion.go
index 2f937388..871ffcac 100644
--- a/chatcompletion.go
+++ b/chatcompletion.go
@@ -242,13 +242,15 @@ type ChatCompletionChoice struct {
 	// A chat completion message generated by the model.
 	Message ChatCompletionMessage `json:"message,required"`
 	// JSON contains metadata for fields, check presence with [respjson.Field.Valid].
-	JSON struct {
-		FinishReason respjson.Field
-		Index        respjson.Field
-		Logprobs     respjson.Field
-		Message      respjson.Field
-		ExtraFields  map[string]respjson.Field
-		raw          string
+	ReasoningContent string `json:"reasoning_content"`
+	JSON             struct {
+		FinishReason     respjson.Field
+		Index            respjson.Field
+		Logprobs         respjson.Field
+		Message          respjson.Field
+		ReasoningContent respjson.Field
+		ExtraFields      map[string]respjson.Field
+		raw              string
 	} `json:"-"`
 }
 
@@ -687,6 +689,8 @@ type ChatCompletionChunkChoiceDelta struct {
 	// Deprecated and replaced by `tool_calls`. The name and arguments of a function
 	// that should be called, as generated by the model.
 	//
+	ReasoningContent string `json:"reasoning_content,nullable"`
+
 	// Deprecated: deprecated
 	FunctionCall ChatCompletionChunkChoiceDeltaFunctionCall `json:"function_call"`
 	// The refusal message generated by the model.
diff --git a/streamaccumulator.go b/streamaccumulator.go
index 3f4d6491..8161d225 100644
--- a/streamaccumulator.go
+++ b/streamaccumulator.go
@@ -121,6 +121,7 @@ func (cc *ChatCompletion) accumulateDelta(chunk ChatCompletionChunk) bool {
 
 		choice.Message.Content += delta.Delta.Content
 		choice.Message.Refusal += delta.Delta.Refusal
+		choice.ReasoningContent += delta.Delta.ReasoningContent
 
 		for j := range delta.Delta.ToolCalls {
 			deltaTool := &delta.Delta.ToolCalls[j]