Batch cooling crystallizers are widely used in the chemical industry. In this study, a dynamic model for change of crystallizer temperature as a function of coolant flow rate and coolant inlet temperature is proposed. The unseeded crystallization of potassium nitrate from aqueous solutions in a semi-pilot batch cooling crystallizer was studied. The model parameters were obtained, and the model predictions compared with experimental results of the crystallizer operation. The model accurately predicts the change of the crystallizer and coolant outlet temperatures, for both uncontrolled and cooling rate feedback controlled operation, hence can be used to develop control strategies and controller tuning for batch cooling crystallizers. The methodology described was also successfully applied to the seeded crystallization of an organic compound in an industrial crystallizer.