The Arrival of GPT-5.5: OpenAI’s New Deep-Thinking Powerhouse

OpenAI has released GPT-5.5 and GPT-5.5 Pro, targeting complex professional and agentic workloads. GPT-5.5 shows strong benchmark results including 82.7% on Terminal-Bench 2.0, 73.1% on Expert-SWE, and topped the Artificial Analysis Intelligence Index by 3 points, breaking a three-way tie with Anthropic and Google. Priced at $5/Mtok input and $30/Mtok output, it is positioned as more token-efficient than GPT-5.4 for hard tasks, often reducing real cost per completed task. The post also notes that in-memory prompt caching is not supported, and that GPT-5.5 is available via the Kilo Gateway, where it is a top recommended model for coding and always-on agent workflows.