This analysis is used to investigate a free flow inclined flat plate solar still. To study the effect of significant parameters on a laminar failing liquid solution over an inclined long flat plate solar still, a mathematical two dimensional flow analysis is carried out based on continuity. momentum and energy equations for liquid and vapor phases together with the interface. As far as the liquid film is concerned, the velocity. film thickness. pressure, temperature and the hourly evaporated water volume profiles are found. It is shown that the significant parameters which affect the solar still are the initial film thickness (i.e, the initial mass flow rate), the plate inclination, the still length and the absorber heat flux (i.e., the solar radiation reaching the plate). It is also shown that the variation in liquid film thickness down the still has a significant effect on the evaporation rate (i.e., the condensed water) and should not be neglected particularly in the case of a long inclined solar still. (C) 2009 Elsevier B.V. All rights reserved.