To do further research on the mass-transfer mechanism in rotating packed bed (RPB), dynamics of droplets in a RPB are studied by an analytical approach combined with a series of laboratory measurements. Based on the results of the fluid dynamics, mathematical models of mass-transfer coefficient and mass-transfer process in RPB are proposed, respectively. Mass-transfer experiments in RPB are also carried out using ethanol-water solution. By comparison, the results of simulation agree well with that of the experiment, which demonstrate that both hydrodynamic model and mass-transfer models can better describe the real conditions of RPB. (c) 2014 American Institute of Chemical Engineers AIChE J, 60: 2705-2723, 2014