This paper presents the investigations on the influence of chemical reaction and mass transfer on magneto-hydrodynamic unsteady free convective flow of a viscous, incompressible fluid past an infinite vertical plate through porous media in the presence of constant suction and heat sink. Numerical solution for the flow problem has been obtained by solving the governing equations using multi-parameter perturbation technique. The results are obtained for velocity, temperature and concentration. The effects of various material parameters are discussed on flow variables and presented by graphs.