In the present investigation efforts have been devoted towards developing ail analysis suitable for heat and mass transfer processes modeling in solar distillation systems, when they are operating at higher temperatures. For this purpose the use of Lewis relation is not new although its validity is based on the assumptions of identical boundary layer concentration and temperature distributions, as well as low mass flux conditions. which are not Usually met in solar distillation systems operating at higher temperatures associated with considerable mass transfer rates. The present analysis, taking into consideration these conditions and the temperature dependence of all pertinent thermophysical properties of the saturated binary mixture of water vapor and dry air, leads to the development of ail improved predictive accuracy model. This model, having undergone successful first order validation against earlier reported measurements from the literature. appears to offer more accurate predictions of the transport processes and mass flow rate yield of solar stills when operated at elevated temperatures. (C) 2009 Published by Elsevier Ltd.