The research results concerning barium sulphate precipitation from the concentrated water solutions of barium chloride by means of crystalline ammonium sulphate addition are presented. The experiments were carried out in a continuous laboratory DTM crystallizer with inner circulation of suspension. A liquid jet-pump device generating ascending/descending flow of medium in a mixing chamber was used. Influences of barium chloride concentration in a feed solution (5-24 mass%), process temperature (303-348 K), mean residence time of suspension in a crystallizer working volume (600-10,800 s) and direction of circulation in jet-pump's mixing chamber on the resulting crystal size distribution of barium sulphate were investigated. Neural network models of the process were elaborated, providing the basis for the theoretical analysis of the influence of hydrodynamic regime on the population density distributions of crystal product. Conformity of the simulated population density distribution data with the experimental ones, as well as with the SDG kinetic model predictions was analyzed, verified and discussed. (C) 2010 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.