OpenAI releases GPT-5.5 Instant, treating it as High capability in Cybersecurity and Biological & Chemical Preparedness categories for the first time in the Instant model line.

GPT-5.5 Instant is OpenAI's latest Instant model. The main baseline model is GPT-5.3 Instant; there is no model named GPT-5.4 Instant.

This is the first Instant model designated as High capability in the Cybersecurity and Biological & Chemical Preparedness categories, with appropriate safeguards implemented accordingly.

The safety mitigation approach for GPT-5.5 Instant follows a similar strategy to previous models in the Instant series. GPT-5.5 (referred to as GPT-5.5 Thinking to avoid confusion with the instant variant) is a separate offering.