GPT-5.5 Pro was released on 23 April 2026 alongside GPT-5.5 and is the high-compute tier of that generation: a 1,050,000-token context window, 128,000 tokens of output, text and image input, and a knowledge cutoff of 1 December 2025 — three months fresher than the GPT-5.4 family.
Two details separate it from GPT-5.4 Pro. Its default reasoning effort is high rather than medium, with xhigh available above that, so the model spends more compute unless told otherwise. And it accepts Batch API requests, which GPT-5.4 Pro does not — a practical difference for anyone processing large volumes offline, where batch pricing applies.
The headline price is unchanged from its predecessor at $30 per million input tokens and $180 per million output. Requests can take several minutes, and OpenAI recommends background mode rather than waiting on a synchronous call.
#pro tier#1M context#xhigh effort#batch supported#professional work