“Instead of carefully managing every step, you can give GPT-5.5 a messy, multi-part task and trust it to plan, use tools, check its work, navigate through ambiguity, and keep going,” according to OpenAI. The company also notes that GPT-5.5 will have its “strongest set of safeguards to date” and can use “significantly fewer” tokens to complete tasks in Codex.

GPT-5.5 will roll out starting Thursday to Plus, Pro, Business, and Enterprise ChatGPT tiers and Codex, with GPT-5.5 Pro coming to Pro, Business, and Enterprise users.

The new model is the latest step in an increasingly heated battle between OpenAI and Anthropic as the companies race to potentially go public later this year. Anthropic recently released Claude Opus 4.7 and also announced Mythos Preview, a non-public model it says is uniquely advanced in cybersecurity. OpenAI quickly followed with GPT-5.4-Cyber, its own model trained to flag cybersecurity vulnerabilities. And both companies are competing to corner the market on AI coding and enterprise tools, with OpenAI recently slashing so-called “side quests” in favor of chasing bigger revenue drivers.

GPT-5.5’s release also comes days before the high-profile trial between Elon Musk and OpenAI executives Sam Altman and Greg Brockman. Proceedings are set to begin on Monday in a federal courtroom in Oakland, California.