Three types of batch crystallization model experiments are considered: a ) crystallization in which a constant supersaturation is maintained throughout the experiment ( e.g. by programmed cooling); b ) crystallization during which supersaturation is produced at a constant rate; c ) crystallization ( e.g. by precipitation) in which an initial supersaturation produced at the beginning gradually decreases during the run. The kinetic data obtained in the first case are of the same kind as those obtained in a continuous MSMPR (mixed suspension - mixed product removal) crystallizer. The two remaining types of experiment, on the other hand, can only provide relative kinetic data with respect to a reference run.