A novel population balance model for the fluidized bed granulation and drying process was developed taking into consideration moisture content for determining the coalescence and breakage probabilities. Experimental data of pharmaceutical powders manufactured at production scale was used to determine the coalescence and breakage rate constant. It was found that the calculated mean volume diameter and frequency distribution showed good agreement with the experimental ones observed during the coalescence growth and the breakage stages. (C) 2018 Elsevier B.V. All rights reserved.