GPT 5.5 Pro

OpenAI’s premium 5.5 variant — top-of-line reasoning at a higher price than 5.5 base, for the hardest agentic and research workloads.

Try GPT 5.5 Pro in the Workbench

Run this model interactively, tune parameters, and compare outputs.

Model ID: gpt-5-5-pro-2026-04-23

GPT 5.5 Pro is OpenAI’s premium-tier reasoning model, the most capable variant of the 5.5 family. Targets the hardest professional workflows — multi-step reasoning, complex coding, deep research, and agentic tasks where accuracy is worth a premium over throughput.

Note: Prompts exceeding 272K input tokens incur 2x input and 1.5x output pricing for the full session.

Metric	Value
Context Length	1,050,000 tokens
Max Output Tokens	128,000 tokens
Multilingual	Yes

Example request

Use the Workbench as a request builder: configure parameters for this model in the UI, then open the API tab to copy the exact cURL or Python call.

Minimal

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-5-5-pro-2026-04-23",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ]
}'

Basic parameters

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-5-5-pro-2026-04-23",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false
}'

All parameters

cURL

curl -X POST https://hub.oxen.ai/api/ai/chat/completions \
  -H "Content-Type: application/json" \
  -H "Authorization: Bearer $OXEN_API_KEY" \
  -d '{
  "model": "gpt-5-5-pro-2026-04-23",
  "messages": [
    {
      "role": "user",
      "content": "Hello, what can you do?"
    }
  ],
  "temperature": 0.7,
  "max_tokens": 1024,
  "stream": false,
  "top_p": 1.0,
  "frequency_penalty": 0,
  "presence_penalty": 0
}'

Fetch model details

The models endpoint returns the full model object, including its json_request_schema.

curl -H "Authorization: Bearer $OXEN_API_KEY" https://hub.oxen.ai/api/ai/models/gpt-5-5-pro-2026-04-23

Request parameters

This model follows the standard OpenAI chat completions request body. See the chat completions reference for the full parameter list.