Double-diffusive natural convection and surface thermal radiation in an inclined cavity that simulates a solar still device is studied numerically. The parameters considered were 10(3) <= Ra-T (Ra-M) <= 10(6), 8 <= A <= 16 and 15 degrees <= theta <= 35 degrees. The steady state 2-D governing equations have been solved by the finite volume method. Streamlines, isotherms, isolines of water vapor, mass flow rate of distillate and average Nusselt and Sherwood numbers as a function of Rayleigh number for different inclination angle are presented. The results show that surface thermal radiation modifies the fluid flow from one-cell to multi-cellular pattern due to the surface thermal radiation increases the velocity near the walls, as a consequence the average convective Nusselt number, the total Nusselt number and the Sherwood number were increased about 25%, 175% and 15%, respectively. The mass flow rate of distillate increases as A, Ra and theta increase. The most suitable case for a solar still device is that for Ra-T = 10(6), A = 16 and theta >= 25 degrees. (C) 2013 Elsevier B.V. All rights reserved.