In this study, we investigated the short-term synergistic CO2 removal effects of an olivine–diatom coculture system by introducing fine-grained olivine powder directly into diatom cultures and observing the biological response. To account for potential interference from olivine particles in cell counting, we conducted additional experiments in which olivine particles were enclosed within a dialysis bag to explore both the direct and indirect influences of diatom growth on olivine dissolution. We assessed the extent by which growth-mediated uptake of H4SiO4 by diatoms accelerated olivine dissolution. Finally, we evaluated the comprehensive CO2 removal efficiency of the olivine–diatom coculture system through the fixation of organic and inorganic carbon.This dataset is included in the OA-ICC data compilation maintained in the framework of the IAEA Ocean Acidification International Coordination Centre (see https://oa-icc.ipsl.fr). Original data were extracted from tables in the related paper (see Related to) by the OA-ICC data curator. In order to allow full comparability with other ocean acidification data sets, the R package seacarb (Gattuso et al, 2024) was used to compute a complete and consistent set of carbonate system variables, as described by Nisumaa et al. (2010). In this dataset the original values were archived in addition with the recalculated parameters (see related PI). The date of carbonate chemistry calculation by seacarb is 2026-05-08.