OpenAI Launches GPT-5.6 Sol, Terra, and Luna

OpenAI has officially launched GPT-5.6, its next-generation model family, in a limited preview that began on June 26, 2026. For the first time, a GPT release ships with a new naming system: Sol, Terra, and Luna identify three permanent capability tiers, while the number marks the generation.

What’s New

GPT-5.6 Sol is OpenAI’s most powerful model to date. It features a 1.5 million token context window, a step up from GPT-5.5’s 1 million limit. OpenAI has also introduced a “max reasoning effort” mode that gives Sol more time to think through hard problems, along with an “ultra mode” that spins up sub-agents to tackle complex tasks in parallel.

The headline improvements are in coding, cybersecurity, and biology. Sol sets a new state of the art on Terminal-Bench 2.1, a benchmark for command-line workflows that require planning and tool coordination. In cybersecurity, OpenAI says it shifts the “performance-efficiency frontier” for tasks like vulnerability research — a capability that partly explains the unusual rollout restrictions.

Terra matches GPT-5.5 performance at roughly half the cost, while Luna brings strong capability at the lowest price point in OpenAI’s lineup.

The Restricted Rollout

This is the first time a major AI model has launched under government-requested restrictions. At the White House’s request, OpenAI is limiting early access to around 20 trusted partner organisations whose participation has been disclosed to the government. The staggered release reflects concerns about the model’s advanced capabilities in sensitive domains.

OpenAI says it plans to make all three tiers broadly available through ChatGPT, Codex, and the API in the coming weeks.

Pricing

API pricing per 1 million tokens:

What This Means for You

If you’re a ChatGPT user, you’ll need to wait a few weeks before GPT-5.6 arrives in the app. When it does, the Sol/Terra/Luna tiers should make it easier to pick the right balance of power and speed for your task.

For developers, Terra is the headline: GPT-5.5-level performance at half the price is a meaningful cost reduction for production workloads. Luna offers a competitive option for high-volume tasks where speed matters more than peak capability.

The government-restricted launch is a notable precedent. It signals that frontier AI releases may increasingly involve regulatory coordination — something worth watching as models continue to advance. For more context on what was expected before the launch, see our earlier coverage.

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