An analysis is presented to investigate the effects of chemical reaction, thermal stratification, Soret number and Dufour number on MHD free convective heat and mass transfer of a viscous, incompressible and electrically conducting fluid on a vertical stretching surface embedded in a saturated porous medium. The governing partial differential equations have been transformed by a similarity transformation into a system of ordinary differential equations, which are solved numerically using a fourth order Runge-Kutta scheme with the shooting method. The results obtained show that the flow field is influenced appreciably by the presence of chemical reaction, thermal stratification Soret number. Dufour number and magnetic field. (C) 2008 Elsevier B.V. All rights reserved.