Pneumatic conveying drying (PCD) has been widely used in industrial production because it is regarded as highly efficient for heating and mass product operation. Drying rate and the time required to dry depend on the drying conditions and thermal properties of the food material. A model was developed to predict heat and mass transfer between rice powder particles defined as spherical in shape and moist air in a PC dryer. The system of coupled non-linear differential equations was solved numerically by means of the Runge-Kutta-Gill method. For validation of the model, data was collected using a trial up-stream pneumatic dryer. The model was successfully validated for its prediction of the moisture content and the temperature of rice powder. Monte Carlo simulations were also carried out to investigate the influence of initial moisture content and particle size distributions on the propagation of the frequency of moisture distribution of the product in a PC dryer. (c) 2008 Elsevier Ltd. All rights reserved.