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Build with GPT-5.5 freeGPT-5.5 vs GPT-5.2 Codex for Research
Which AI model is better for research? We compare GPT-5.5 and GPT-5.2 Codex on the criteria that matter most - with a clear verdict.
Why your research LLM choice matters
Research applications push LLMs to their limits - requiring synthesis across multiple long documents, careful reasoning about conflicting evidence, and structured output that meets academic standards. Context window size and factual accuracy are the two most critical factors: a model that summarises confidently but incorrectly is actively harmful in a research context.
Key evaluation criteria for research
Side-by-Side Comparison
| Feature | GPT-5.5Winner | GPT-5.2 Codex |
|---|---|---|
| Provider | OpenAI | OpenAI |
| Model Type | text | text |
| Context Window | 1,000,000 tokens | 400,000 tokens |
| Input Cost | $5.00/ 1M tokens | $1.75/ 1M tokens |
| Output Cost | $30.00/ 1M tokens | $14.00/ 1M tokens |
| Top pick for Research |
Strengths for Research
GPT-5.5
OpenAI1. Strongest Agentic Coding Model
- State-of-the-art on Terminal-Bench 2.0 (82.7%), Expert-SWE (73.1%), and SWE-Bench Pro (58.6%), outperforming GPT-5.4 on complex coding tasks.
- Holds context across large systems, reasons through ambiguous failures, and carries changes through surrounding codebases with fewer tokens.
2. Higher Intelligence at GPT-5.4 Latency
- Co-designed, trained, and served on NVIDIA GB200/GB300 NVL72 systems to match GPT-5.4 per-token latency while performing at a significantly higher level.
- Uses fewer tokens to complete the same tasks, making it more efficient as well as more capable.
3. Powerful for Knowledge Work & Computer Use
- Scores 84.9% on GDPval (44 occupations) and 78.7% on OSWorld-Verified for autonomous computer operation.
- Excels at generating documents, spreadsheets, and reports; naturally moves across finding information, using tools, and checking output.
4. Scientific Research Co-Scientist
- Leading performance on GeneBench, BixBench, and FrontierMath; helped discover a new proof about Ramsey numbers verified in Lean.
- Strong enough to meaningfully accelerate progress at the frontiers of biomedical and mathematical research.
GPT-5.2 Codex
OpenAI1. Optimized for Long-Horizon Coding Tasks
- OpenAI describes GPT-5.2 Codex as a highly intelligent coding model built for long-horizon, agentic coding work.
- Well suited to planning, refactoring, debugging, and multi-step implementation flows inside real codebases.
2. Adjustable Reasoning for Coding Work
- Supports configurable reasoning effort from low to xhigh depending on speed and quality needs.
- Accepts both text and image inputs while producing text output.
3. Large Context + Long Output
- 400 k token context window supports broad repository understanding and larger working sets.
- Allows up to 128 k output tokens for longer patches, code generation, and technical explanations.
4. Up-to-Date Model Snapshot
- Knowledge cut-off of Aug 31 2025 keeps it current with newer tools and frameworks.
- Supports streaming, function calling, and structured outputs for tool-driven coding workflows.
Verdict: Best LLM for Research
For research tasks, GPT-5.5 edges ahead based on its performance profile and design priorities. It scores higher on depth and accuracy of scientific reasoning - the criterion that matters most for research workflows.
That said, GPT-5.2 Codex remains a strong option. If structured output for reports and papers is a higher priority than raw performance, or if your team is already using OpenAI's tooling, GPT-5.2 Codex can deliver strong results for research workloads.
With Appaca, you can build research apps powered by either model and switch between them at any time - no rebuild required. Test what actually performs best for your users before committing.
You know GPT-5.5 wins for research. Now build with it.
Most teams spend days comparing models and hours copy-pasting prompts. With Appaca, you build a dedicated research app - powered by GPT-5.5 - in minutes. No code, no re-prompting, runs on any device.
Free to start. Switch models any time. No rebuild required.
Build a research app with GPT-5.5 - freeFrequently asked questions
Is GPT-5.5 or GPT-5.2 Codex better for research?
For research tasks, GPT-5.5 has the edge based on its performance profile and design priorities. It ranks higher on depth and accuracy of scientific reasoning, which is the most important criterion for research workflows. That said, both models can handle research workloads - the best choice depends on your specific requirements and budget.
What are the key differences between GPT-5.5 and GPT-5.2 Codex for research?
The main differences are in depth and accuracy of scientific reasoning, ability to synthesise multi-document context, citation awareness and factual grounding. GPT-5.5 is developed by OpenAI and shares the same provider as GPT-5.2 Codex. Context window, pricing, and speed all differ - check the comparison table above for a side-by-side breakdown.
How much does it cost to use GPT-5.5 vs GPT-5.2 Codex?
GPT-5.2 Codex is cheaper at $1.75/million input tokens, versus $5.00/million for GPT-5.5. For research workloads, the total cost difference depends on your average prompt length and volume.
Can I build a research app with GPT-5.5 or GPT-5.2 Codex?
Yes. Both models can power research applications. With Appaca, you can build a research app using either GPT-5.5 or GPT-5.2 Codex - and switch between them at any time to find the model that performs best for your specific workflow, without rebuilding your product.
Which model should I choose if I care most about depth and accuracy of scientific reasoning?
GPT-5.5 is the stronger choice when depth and accuracy of scientific reasoning is your top priority. It ranks #1 overall for research tasks. If cost or latency are constraints, GPT-5.2 Codex may still meet your needs at a lower cost.