diff --git a/chat.go b/chat.go
index 2f1467e..360a69d 100644
--- a/chat.go
+++ b/chat.go
@@ -274,6 +274,7 @@ type ChatCompletionRequest struct {
 	// Metadata to store with the completion.
 	Metadata         map[string]string `json:"metadata,omitempty"`
 	IncludeReasoning *bool             `json:"include_reasoning,omitempty"`
+	ReasoningFormat  *string           `json:"reasoning_format,omitempty"`
 	// Configuration for a predicted output.
 	Prediction *Prediction `json:"prediction,omitempty"`
 	// ChatTemplateKwargs provides a way to add non-standard parameters to the request body.