Ai2 releases MolmoAct 2, a fully open robot action-reasoning model that beats π0.5 on real-world tasks
Confirmed
The takeaway
On 2026-05-05 the Allen Institute for AI released MolmoAct 2 and MolmoAct 2-Think, open vision-language-action models built on the Molmo2-ER embodied-reasoning VLM with a flow-matching action expert, along with weights, code and 720+ hours of bimanual data.
Status
- Claim
Confirmed
- Our reporting
- High confidence
- Importance
- 2 of 5
- Last verified
- 29 September 2026
Your AI and this story
- GPT-6 Astra5 days after its cutoff
- Claude Opus 5.5In its training data
- Gemini 4 Hydrogen35 days after its cutoff
- Grok 4.7In its training data
It is after the cutoff of GPT-6 Astra and Gemini 4 Hydrogen, and can be in the training data of Claude Opus 5.5 and Grok 4.7.
Key facts
- Paper: ‘MolmoAct2: Action Reasoning Models for Real-world Deployment’ (arXiv 2605.02881); weights on HF 2026-05-04/05
- Real-world Franka, 15 tasks: 87.1% vs 48.4% (MolmoBot) and 45.2% (π0.5), Ai2’s own evaluation
- LIBERO: 97.2% (base), 98.1% (Think) vs ~86.6% for MolmoAct
- Latency: ~180 ms per action call (790 ms with adaptive depth reasoning) vs 6,700 ms for MolmoAct
- Molmo2-ER averages 63.8 across 13 embodied-reasoning benchmarks, ahead of GPT-5, Gemini 2.5 Pro and Gemini Robotics-ER 1.5 (Ai2)
- Data: MolmoAct2-BimanualYAM (720+ h), re-annotated DROID/SO-100/BC-Z/Fractal mixture; open FAST tokenizer; code Apache-2.0
What happened
MolmoAct 2 is the successor to Ai2’s 2025 MolmoAct, which reasoned in 3D. It swaps in a stronger embodied-reasoning backbone (Molmo2-ER, trained on ~3M extra examples) and adds a separate continuous action expert, which cuts latency sharply. Everything is released: weights, training data and code, with LeRobot integration.
Why it matters
It is the most capable fully open VLA stack, with open data as well as weights. Academic labs can reproduce and extend it, unlike closed π, Gemini Robotics or Helix models. The comparisons with π0.5 are Ai2’s own.
Sources
5 sources from 5 sites. Numbers match the chips in the text.
5 sources: 4 primary, 1 press
Primary
- Ai2 blog: MolmoAct 2allenai.org, official
- arXiv 2605.02881arxiv.org, paper
- Hugging Face: MolmoAct2 modelshuggingface.co, code
- GitHub: allenai/molmoact2github.com, code
Press
- SiliconANGLE: Ai2 releases MolmoAct 2siliconangle.com, press
Changes
- Filed