The second edition (14–15 September 2026) of the Chemistry Days of the Generic Planetary Climate Model (G-PCM) brought together 17 participants at the LMD to discuss current research and future developments in atmospheric chemistry for planetary climate models. The workshop focused on two major developments: coupling photochemical haze production with radiative transfer and implementing high-temperature chemistry for hot planetary atmospheres. Presentations, hands-on sessions and discussions led to concrete development plans, including new chemistry features, dedicated test cases and improvements to the model’s chemical framework. The event was funded by SF2A and the ERC OxyPlanets project (grant agreement No. 101053033).