diff --git a/packages/core/src/model/nodes/ChatNode.ts b/packages/core/src/model/nodes/ChatNode.ts
index 72d25f67..56a2529c 100644
--- a/packages/core/src/model/nodes/ChatNode.ts
+++ b/packages/core/src/model/nodes/ChatNode.ts
@@ -16,6 +16,7 @@ import {
   openaiModels,
   streamChatCompletions,
   type ChatCompletionTool,
+  chatCompletions,
 } from '../../utils/openai.js';
 import retry from 'p-retry';
 import type { Inputs, Outputs } from '../GraphProcessor.js';
@@ -892,9 +893,7 @@ export class ChatNodeImpl extends NodeImpl<ChatNode> {
           const options: Omit<ChatCompletionOptions, 'auth' | 'signal'> = {
             messages: completionMessages,
             model: finalModel,
-            temperature: useTopP ? undefined : temperature,
             top_p: useTopP ? topP : undefined,
-            max_tokens: maxTokens,
             n: numberOfChoices,
             frequency_penalty: frequencyPenalty,
             presence_penalty: presencePenalty,
@@ -907,6 +906,15 @@ export class ChatNodeImpl extends NodeImpl<ChatNode> {
             ...additionalParameters,
           };
 
+          const isO1Beta = finalModel.startsWith('o1-preview') || finalModel.startsWith('o1-mini');
+
+          if (isO1Beta) {
+            options.max_completion_tokens = maxTokens;
+          } else {
+            options.temperature = useTopP ? undefined : temperature; // Not supported in o1-preview
+            options.max_tokens = maxTokens;
+          }
+
           const cacheKey = JSON.stringify(options);
 
           if (this.data.cache) {
@@ -918,6 +926,54 @@ export class ChatNodeImpl extends NodeImpl<ChatNode> {
 
           const startTime = Date.now();
 
+          if (isO1Beta) {
+            const response = await chatCompletions({
+              auth: {
+                apiKey: context.settings.openAiKey ?? '',
+                organization: context.settings.openAiOrganization,
+              },
+              headers: allAdditionalHeaders,
+              signal: context.signal,
+              timeout: context.settings.chatNodeTimeout,
+              ...options,
+            });
+
+            if (isMultiResponse) {
+              output['response' as PortId] = {
+                type: 'string[]',
+                value: response.choices.map((c) => c.message.content!),
+              };
+            } else {
+              output['response' as PortId] = {
+                type: 'string',
+                value: response.choices[0]!.message.content!,
+              };
+            }
+
+            if (!isMultiResponse) {
+              output['all-messages' as PortId] = {
+                type: 'chat-message[]',
+                value: [
+                  ...messages,
+                  {
+                    type: 'assistant',
+                    message: response.choices[0]!.message.content!,
+                    function_calls: undefined,
+                    isCacheBreakpoint: false,
+                    function_call: undefined,
+                  },
+                ],
+              };
+            }
+
+            output['duration' as PortId] = { type: 'number', value: Date.now() - startTime };
+
+            Object.freeze(output);
+            cache.set(cacheKey, output);
+
+            return output;
+          }
+
           const chunks = streamChatCompletions({
             auth: {
               apiKey: context.settings.openAiKey ?? '',
diff --git a/packages/core/src/utils/openai.ts b/packages/core/src/utils/openai.ts
index 1487152d..e5f1699b 100644
--- a/packages/core/src/utils/openai.ts
+++ b/packages/core/src/utils/openai.ts
@@ -158,6 +158,38 @@ export const openaiModels = {
     },
     displayName: 'GPT-4o mini (2024-07-18)',
   },
+  'o1-preview': {
+    maxTokens: 128000,
+    cost: {
+      prompt: 0.0015,
+      completion: 0.006,
+    },
+    displayName: 'o1-preview',
+  },
+  'o1-preview-2024-09-12': {
+    maxTokens: 128000,
+    cost: {
+      prompt: 0.0015,
+      completion: 0.006,
+    },
+    displayName: 'o1-preview (2024-09-12)',
+  },
+  'o1-mini': {
+    maxTokens: 128000,
+    cost: {
+      prompt: 0.0003,
+      completion: 0.0012,
+    },
+    displayName: 'o1-mini',
+  },
+  'o1-mini-2024-09-12': {
+    maxTokens: 128000,
+    cost: {
+      prompt: 0.0003,
+      completion: 0.0012,
+    },
+    displayName: 'o1-mini (2024-09-12)',
+  },
   'local-model': {
     maxTokens: Number.MAX_SAFE_INTEGER,
     cost: {
@@ -258,6 +290,10 @@ export type ChatCompletionOptions = {
   temperature?: number;
   top_p?: number;
   max_tokens?: number;
+
+  /** Only for o1 series of models. Otherwise max_tokens. */
+  max_completion_tokens?: number;
+
   n?: number;
   stop?: string | string[];
   presence_penalty?: number;
@@ -414,6 +450,31 @@ export type ChatCompletionFunction = {
   strict: boolean;
 };
 
+export async function chatCompletions({
+  endpoint,
+  auth,
+  signal,
+  headers,
+  timeout,
+  ...rest
+}: ChatCompletionOptions): Promise<ChatCompletionResponse> {
+  const abortSignal = signal ?? new AbortController().signal;
+
+  const response = await fetch(endpoint, {
+    method: 'POST',
+    headers: {
+      'Content-Type': 'application/json',
+      Authorization: `Bearer ${auth.apiKey}`,
+      ...(auth.organization ? { 'OpenAI-Organization': auth.organization } : {}),
+      ...headers,
+    },
+    body: JSON.stringify(rest),
+    signal: abortSignal,
+  });
+
+  return response.json();
+}
+
 export async function* streamChatCompletions({
   endpoint,
   auth,