In this research the objective is to study the effects of thermal radiation and chemical reaction on mass transfer on unsteady free convection flow past an exponentially accelerated infinite vertical plate through porous medium in the presence of magnetic field. First of all we described the basic concepts of MHD flow. Then the resultant expressions for velocity profiles, temperature profiles, concentration profiles, skin friction profiles, rate of heat transfer profiles and rate of mass transfer profiles of the fluid have been obtained with the help of the different physical parameters. The fluid is considered here as absorbing or emitting radiation but a non-scattering medium. We used proper transformations to make the governing equations dimensionless. The dimensionless governing equations are reduced to a set of ordinary differential equations. Then we solve these equations with the help of "perturbation technique". At last the effects of various parameters on the velocity profiles, temperature profiles, concentration profiles, skin friction profiles, rate of heat transfer profiles and rate of mass transfer profiles are shown graphically.