Osmotic dehydration is a cheap alternative in the partial removal of water during the production of dried fruits. Generally, the production process is completed with conventional drying, and both the removal methods can be described by diffusion. This article presents a detailed three-dimensional description of the water removal from semi-mature coconut slices parallelepiped-shaped, using a diffusion model. Coconut pieces were submitted to osmotic dehydration, using a solution of sucrose and water in a concentration of 35 degrees Brix, at temperature of 40 degrees C, followed by convective drying at 50, 60 and 70 degrees C. The analytical solution of the three-dimensional diffusion equation was coupled to an optimizer, and the process parameters were determined using the obtained experimental data. The analysis of the results makes it possible to conclude that the model with boundary condition of the third kind satisfactorily describes the diffusion processes. (C) 2012 Elsevier Ltd. All rights reserved.