in this second of two papers, we investigated the influence of process parameters on BaSO(4) particle precipitation in a hollow fiber membrane device. The solution of barium chloride was passed tangentially over the membrane surface and reacted with a solution of K(2)SO(4) introduced through the membrane pores. The resulting supersaturation induced nucleation and particle growth on the lumen side of the hollow fibers. A specific technique was developed to measure crystal size directly at the outlet of the hollow fiber device by using EDTA as a neutralizing agent of crystal nucleation and growth. Concentrations of barium chloride and potassium sulphate were shown to influence mainly the CSD, the effect of inlet flow rates on the lumen and shell sides being less pronounced. The chemical conversions measured were between 3.7% and 20.5%. We propose improvements in the design of hollow fiber devices in order to give higher chemical conversions.