This paper presents a dynamic model of a bubble column reactor with particle formation, accomplished by adopting a hybrid CFD-reaction engineering approach. CFD is employed for estimating the hydrodynamics and is based on the two-phase Eulerian-Eulerian viewpoint. The reaction engineering model links the penetration theory to a population balance that includes particle formation and growth with the aim of predicting the average particle size. The model is then applied to the precipitation of CaCO3 via CO2 absorption into Ca(OH)(2)aq in a draft tube bubble column and draws insight into the phenomena underlying the crystal size evolution.