A model of heat and mass transfer phenomena in a trapezoidal cavity is established. This work is partly based on the experimental results obtained in the case of a trapezoidal-shaped solar distiller. The resolution of the related system of equations gives results that are in a good agreement with those obtained experimentally. The modeling was made on the basis of a stagnant zone within the closed cavity, whose walls are at different temperatures. The numerical simulation could contribute to the study and design of numerous applications such small solar distillation units, solar driers and solar greenhouses, among others. (C) 2014 Elsevier BY. All rights reserved.