A numerical model is. proposed to describe the process of drying a parallelepipedic oil shale particle. Assuming Fick's law, the diffusion equation for the shape of the particle was used. The objective of the study was to develop a computer program in Fortran to estimate the moisture content,of an oil shale particle undergoing drying as a function of time and position. The average moisture content was also obtained. The model takes into account the migration of water by diffusion within the solid and its loss at the interface. The model results were compared to experimental data from an apparatus which measured the mass loss of a particle. The apparatus comprised an electronic balance attached by a thin wire to the particle placed inside an incubator.222233238