This article proposes a numerical solution of the diffusion equation for solids obtained by revolution of arbitrarily shaped plane surfaces for the description of heat transfer or mass transport. The diffusion equation is discretized and solved using the finite volume method with fully implicit formulation, generalized coordinates and boundary condition of the first kind. The proposed solution exploits symmetry conditions, which reduces the problem to the two-dimensional case, and it diminishes significantly the computational effort in comparison with the traditional method using three-dimensional grids. Our solution is applied to - and compared with - the drying kinetics of solids with known analytical solutions of the diffusion equation. Both solutions agree well in all analyzed cases. Furthermore, our solution is used to describe the moisture distribution inside solids. (C) 2009 Elsevier Ltd. All rights reserved.