Carbon capture and storage (CCS) technology is considered as a viable alternative for reducing a large amount of CO2 gas discharged from power plants and steel production plants. CO2 storage is a part of the CCS to keep the discharged CO2 at deep sub-seabed geological areas. A leakage of this stored CO2 may result in a CO2 bubble plume which causes a pH reduction and an increase in pCO2 (partial pressure of CO2) of the ocean environment due to the ocean acidification between the leaked CO2 and the seawater. Consequently, this leads environmental influence on the marine life. Thus, the aim of this study is to present an implement of computational fluid dynamics coupled with population balance model to simulate behaviors of a leaked CO2 bubble plume via the ocean CO2 storage against a recently published experiment. The simulated behaviors include the momentum and the processes of breakup, coalescence and mass-transfer which can account for the rising velocity and the size distribution of the CO2 bubbles in the plume. The applied models also can predict the changes in pH and pCO2 of the seawater during the occurrence of the leakage. It was found that the predicted results had a good agreement compared to the published experimental data. © 2016 The Authors.