Numerical results of two dimensional double diffusive natural convection in a square porous cavity submitted to cross gradients of heat and solute concentration are reported in this study. The parameters governing the problem are the thermal Rayleigh number (100less than or equal toRaless than or equal to200), the Lewis number (0.1 less than or equal to Le less than or equal to 10) and the buoyancy ratio (-10 less than or equal to N less than or equal to 10). The effects of the governing parameters on the flow structure and heat and mass transfer are analyzed. It is demonstrated that the solutal buoyancy force induced by horizontal concentration gradients eliminates the multiplicity of solutions obtained in pure thermal convection when N exceeds some critical value, which depends on Le and Ra. For N > 0/(N < 0), the monocellular trigonometric/(clockwise) solution is maintained for all the explored ranges of the governing parameters considered in this study. (C) 2003 Elsevier Ltd. All rights reserved.