Mathematical modeling and computer simulation form a powerful method for better understanding the physical process of drying. In this study, a computer program has been developed for simulating a non-equilibrium partial differential equation model for drying rough rice in a deep bed batch dryer. The model consists of four non-linear partial differential equations as a result of the heat and mass balances, together with an appropriate empirical thin layer equation. The set of equations is solved using a finite difference method. Validation of the computer simulation was checked in a laboratory scale rough rice batch dryer under various conditions, which included combinations of two parameters: drying air temperature and mass flow rate. There was good agreement between the simulated and measured average moisture content values along the depth of the dryer bed during the drying process. (c) 2006 Elsevier Ltd. All rights reserved.