To elucidate how bivalve larvae can overcome the physicochemical barriers imposed by adverse carbonate chemistry through biologically controlled biomineralization, we exposed Hong Kong oyster (Magallana hongkongensis) embryos to favorable carbonate chemistry (control, nominal pH 8.1) and adverse carbonate chemistry (treatment, nominal pH 7.4) conditions until prodissoconch I completion.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 downloaded from figshare (see Source) 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 2025-12-31.