diff --git a/libs/langchain-groq/src/chat_models.ts b/libs/langchain-groq/src/chat_models.ts
index 524782a6e49e..49bba333c6de 100644
--- a/libs/langchain-groq/src/chat_models.ts
+++ b/libs/langchain-groq/src/chat_models.ts
@@ -660,6 +660,8 @@ export class ChatGroq extends BaseChatModel<
 
   streaming = false;
 
+  apiKey?: string;
+
   static lc_name() {
     return "ChatGroq";
   }
@@ -690,6 +692,7 @@ export class ChatGroq extends BaseChatModel<
       apiKey,
       dangerouslyAllowBrowser: true,
     });
+    this.apiKey = apiKey;
     this.temperature = fields?.temperature ?? this.temperature;
     this.modelName = fields?.model ?? fields?.modelName ?? this.model;
     this.model = this.modelName;
diff --git a/libs/langchain-groq/src/tests/chat_models.test.ts b/libs/langchain-groq/src/tests/chat_models.test.ts
index b1ed1988d647..8f6b06f13edb 100644
--- a/libs/langchain-groq/src/tests/chat_models.test.ts
+++ b/libs/langchain-groq/src/tests/chat_models.test.ts
@@ -10,3 +10,11 @@ test("Serialization", () => {
     `{"lc":1,"type":"constructor","id":["langchain","chat_models","groq","ChatGroq"],"kwargs":{"api_key":{"lc":1,"type":"secret","id":["GROQ_API_KEY"]}}}`
   );
 });
+
+test("Serialization with no params", () => {
+  process.env.GROQ_API_KEY = "foo";
+  const model = new ChatGroq();
+  expect(JSON.stringify(model)).toEqual(
+    `{"lc":1,"type":"constructor","id":["langchain","chat_models","groq","ChatGroq"],"kwargs":{"api_key":{"lc":1,"type":"secret","id":["GROQ_API_KEY"]}}}`
+  );
+});