Jakub Pachocki
Chief Scientist at OpenAI; overall pretraining lead for GPT-4; set research direction for OpenAI Five
Jakub Pachocki is OpenAI's Chief Scientist, as named in a September 2025 OpenAI developer blog post, and is listed with an OpenAI affiliation on a September 2026 paper. The GPT-4 Technical Report credits Pachocki as overall lead and optimization lead for pretraining, and the Dota 2 paper says Pachocki and Szymon Sidor set research direction throughout the OpenAI Five project. The OpenAI o1 System Card lists Pachocki in both the reasoning research leadership and executive leadership, and Pachocki appears among the contributors to the gpt-oss-120b and gpt-oss-20b model card.123456
Work
gpt-ossOpen weights
Listed among the contributors to the gpt-oss-120b and gpt-oss-20b model card (2025); the openai/gpt-oss repository is under the Apache 2.0 license.67
GPT-4 pretraining (external site: arxiv.org)Proprietary product
Credited in the GPT-4 Technical Report (2023) as overall lead and optimization lead among the pretraining core contributors.3
OpenAI Five (external site: arxiv.org)Published research
Co-author of "Dota 2 with Large Scale Deep Reinforcement Learning" (2019); the paper's contributions section says Pachocki and Szymon Sidor set research direction throughout the project, including the first version of the Rapid system for large-scale RL.4
OpenAI o1 (external site: arxiv.org)Proprietary product
Listed under reasoning research leadership and executive leadership in the OpenAI o1 System Card (2024).5
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