A computer-based dynamic model of an eutectic freeze crystallizer comprised of coupled kinetics, population, mass, and energy balances has been developed to simulate its transient behaviour. The model assumed an MSMPR crystallizer and was used to simulate the transient responses of crystal size distribution of salt and ice during the start-up of the crystallizer. The temperature and the solute concentration inside the crystallizer achieved constant values after two residence times, whereas the steady state of the crystal size distributions were reached after ten residence times. A coupled effect of the simultaneous crystallization of salt and ice was clearly visible when the high mass production rate of ice induced the occurrence of a second peak of the supersaturation of salt. (C) 2002 Elsevier Science B.V. All rights reserved.