What OpenAI models support thinking, custom temperature, or both?

I ran a quick check against OpenAI models released in the last six months. “Thinking” here means the model accepted reasoning.effort; “custom temperature” means it accepted a non-default temperature parameter in the test.

What’s interesting to me is the number of models where it appears inconsistent. I wonder why this is?

Why does 5.5 NOT support custom temperature, but 5.4 does?

Model Created Thinking Custom temperature
gpt-5.5-2026-04-23 2026-04-23 Supported Unsupported
gpt-5.5-pro-2026-04-23 2026-04-23 Supported Unsupported
gpt-5.5-pro 2026-04-22 Supported Unsupported
gpt-5.5 2026-04-22 Supported Unsupported
gpt-5.4-mini-2026-03-17 2026-03-17 Supported Supported
gpt-5.4-nano-2026-03-17 2026-03-17 Supported Supported
gpt-5.4-mini 2026-03-14 Supported Supported
gpt-5.4-nano 2026-03-14 Supported Supported
gpt-5.4 2026-03-05 Supported Supported
gpt-5.4-2026-03-05 2026-03-05 Supported Supported
gpt-5.4-pro-2026-03-05 2026-03-05 Supported Unsupported
gpt-5.4-pro 2026-03-04 Supported Unsupported
gpt-5.3-chat-latest 2026-02-27 Supported Unsupported
gpt-4o-search-preview 2026-02-24 Unknown Unsupported
gpt-5.3-codex 2026-02-08 Supported Supported
gpt-5.2-codex 2025-12-19 Supported Unsupported
gpt-5.2-2025-12-11 2025-12-11 Supported Supported
gpt-5.2-pro-2025-12-11 2025-12-11 Supported Unsupported
gpt-5.2-chat-latest 2025-12-10 Supported Unsupported
gpt-5.2-pro 2025-12-10 Supported Unsupported
gpt-5.2 2025-12-09 Supported Supported
gpt-5.1-codex-max 2025-11-20 Supported Unsupported
gpt-5.1-codex-mini 2025-11-13 Supported Unsupported
gpt-5.1-2025-11-13 2025-11-13 Supported Supported
gpt-5.1-codex 2025-11-12 Supported Unsupported
gpt-5.1 2025-11-10 Supported Supported
gpt-5.1-chat-latest 2025-11-07 Supported Unsupported