Abstract: The Dufour and Soret effects on the unsteady two-dimensional magnetohydrodynamics (MHD) double-diffusive free convective flow of an electrically conducting fluid past a vertical plate embedded in a non-Darcy porous medium are investigated numerically. The governing non-linear dimensionless equations are solved by an implicit finite difference scheme of the Crank-Nicolson type with a tridiagonal matrix manipulation. The effects of various parameters entering into the problem on the unsteady dimensionless velocity, temperature, and concentration profiles are studied in detail. Furthermore, the time variation of the skin friction coefficient, the Nusselt number, and the Sherwood number is presented and analyzed. The results show that the unsteady velocity, temperature, and concentration profiles are substantially influenced by the Dufour and Soret effects. When the Dufour number increases or the Soret number decreases, both the skin friction and the Sherwood number decrease, while the Nusselt number increases. It is found that, when the magnetic parameter increases, the velocity and the temperature decrease in the boundary layer.