GPT-5.5 Pro
OpenAIApr 24, 2026N/A
Extended-deliberation tier from April's GPT-5.5 generation, positioned for hardest single-shot reasoning. Now superseded by GPT-5.6 Sol for most workloads.
- Status
- Generally available
- License
- Proprietary API
- Context window
- 400K
- Max output
- 128K
- Input · $/M
- —
- Output · $/M
- —
- Cached input · $/M
- —
- Blended · $/M
- —
- Parameters
- Undisclosed
- Inputs
- Text + images
Benchmarks
This model has no published scores on the benchmarks we track yet. Specs and pricing below the fold are still fully sourced.
Reasoning & knowledge
GPQA Diamond
no public score
MMLU-Pro
no public score
Humanity's Last Exam
no public score
ARC-AGI-2
no public score
Coding
SWE-bench Verified
no public score
SWE-bench Pro
no public score
LiveCodeBench
no public score
Agents & computer use
Terminal-Bench 2
no public score
OSWorld 2.0
no public score
BrowseComp
no public score
Math
AIME 2026
no public score
Known strengths
- Deep deliberation mode
- Enterprise availability
Caveats
- Being phased down since the 5.6 launch; check current API deprecation list