An investigation is carried out to analyze the unsteady MHD free convection, heat and mass transfer flow of a Newtonian fluid past an infinite vertical porous plate with homogeneous chemical reaction and heat absorption/generation. A uniform magnetic field is applied perpendicular to the plate. The non dimensional governing equations are solved numerically by using finite difference method. The effects of various parameters governing the flow on velocity, temperature, concentration, skin friction, Nusselt number and Sherwood number are studied through graphs. It is noticed that velocity decreases with an increase in Magnetic field while it increases with an increase in Grashof number, modified Grashof number& Permeability parameter. Temperature increases with an increase in heat absorption and it shows reverse effect in the case of heat generation and Prandtl number. Concentration decreases with increase in Schmidt number and chemical reaction parameter.