# Mellum2-12B-A2.5B-Thinking vs Qwen3.5 397B (Reasoning)

> Side-by-side benchmark comparison for Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B (Reasoning) across agentic, coding, multimodal, knowledge, reasoning, multilingual, and math tasks.

- Canonical page: https://benchlm.ai/compare/mellum2-12b-a2-5b-thinking-vs-qwen3-5-397b-reasoning
- Last updated: September 4, 2026

- Shared sourced benchmarks: 0
- HTML indexing: indexable
- Ranking lane: BenchAlign v5

## Quick Verdict

No benchmark verdict yet: there is no shared sourced benchmark row for Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B (Reasoning).

## Summary

- Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B (Reasoning) do not currently share a sourced benchmark row. The mirror therefore compares metadata, pricing, context windows, and each model's separately reported coverage without naming a benchmark winner.

## Model Snapshot

| Property | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B (Reasoning) |
|----------|----------|----------|
| Creator | JetBrains | Alibaba |
| Type | Open Weight | Open Weight |
| Reasoning | Reasoning | Reasoning |
| Context | 128K | 128K |
| Independent public score (not head-to-head) | null | 58.89 |
| Benchmarks Covered | 6 | 0 |
| Pricing (input/output) | N/A | $0.60 / $3.60 |

## Category Breakdown

### Agentic

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.3 (Estimated · #76/151)
- Qwen3.5 397B (Reasoning) public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| BFCL v4 | 45.6% | Coming soon | Coming soon |

### Coding

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B (Reasoning) public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| LiveCodeBench v6 | 69.9% | Coming soon | Coming soon |

### Knowledge

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: 48.8 (Estimated · #96/181)
- Qwen3.5 397B (Reasoning) public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| MMLU-Redux | 86.2% | Coming soon | Coming soon |
| GPQA | 57.6% | Coming soon | Coming soon |
| GPQA-D | 57.6% | Coming soon | Coming soon |

### Instruction Following

- Winner: Insufficient shared evidence
- Mellum2-12B-A2.5B-Thinking public-lane score: Coming soon
- Qwen3.5 397B (Reasoning) public-lane score: Coming soon

| Benchmark | Mellum2-12B-A2.5B-Thinking | Qwen3.5 397B (Reasoning) | Winner |
|-----------|-----------|-----------|--------|
| IFEval | 76.5% | Coming soon | Coming soon |

## FAQ

### Can I compare Mellum2-12B-A2.5B-Thinking and Qwen3.5 397B (Reasoning) on BenchLM yet?

Not fully yet. BenchLM is tracking both models, but sourced benchmark coverage is still incomplete for a fair score-level comparison.

### Why does this page show "coming soon" values?

BenchLM only calls winners when public benchmark coverage is available on both sides of the comparison.

## Related Comparisons

- [Mellum2-12B-A2.5B-Thinking vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-mellum2-12b-a2-5b-thinking)
- [Qwen3.5 397B (Reasoning) vs Mellum2-12B-A2.5B-Instruct](/compare/mellum2-12b-a2-5b-instruct-vs-qwen3-5-397b-reasoning)
- [Mellum2-12B-A2.5B-Thinking vs Qwen3.5 397B](/compare/mellum2-12b-a2-5b-thinking-vs-qwen3-5-397b)
- [Qwen3.5 397B (Reasoning) vs Qwen3.5 397B](/compare/qwen3-5-397b-vs-qwen3-5-397b-reasoning)

## Explore More

- [Mellum2-12B-A2.5B-Thinking profile](/models/mellum2-12b-a2-5b-thinking)
- [Qwen3.5 397B (Reasoning) profile](/models/qwen3-5-397b-reasoning)
- [Compare Pricing](/llm-pricing)
- [Alternative Finder](/tools/alternative-finder)
- [LLM Selector](/tools/llm-selector)
- [Overall Rankings](/best/overall)