The investigation is undertaken to study the thermal diffusion and radiation effects on unsteady MHD heat and mass transfer flow past a semi-infinite inclined porous plate embedded in a porous medium in a slip flow regime with variable suction in the presence of first order chemically reaction. The analytical solutions for velocity, temperature and concentration fields are obtained by reducing the governing nonlinear coupled partial differential equations in dimensionless form into a system of ordinary differential equations, using perturbation method. The effect of pertinent flow parameters on velocity, temperature, concentration, the skin friction, the rate of heat transfer and the rate of mass transfer are studied graphically.