A unique model is developed in this paper to describe the behavior of crystal growth in a fluidized-bed crystallizer operated in a batch mode. It is assumed that the liquid phase moves upward through the bed in plug flow and the solid phase in the fluidized bed is perfectly classified. This model can determine the variations of the crystal size, the solution concentration, and the voidage along the bed height during the operation. Subsequently, it can predict the resulting size distribution of the crystals and allow to determine the maximum bed height attainable in operation of a fluidized-bed crystallizer.