This manuscript presents a detailed numerical study on the influence of radiation absorption and chemical reaction on unsteady magneto hydrodynamic free convective heat and mass transfer flow. A heat generating Casson fluid past an oscillating vertical plate embedded in a porous medium in the presence of constant wall temperature and concentration is considered. The non-dimensional governing equations along with the corresponding boundary conditions are solved using Finite difference method numerically. Effects of various emerging flow parameters on concentration, temperature and velocity distributions are presented graphically and analyzed. Expressions for skin-friction, Nusselt number and Sherwood number are also obtained. Effects of radiation absorption and homogeneous chemical reaction are considered here. It is interesting to note that, the presence of the chemical reaction reduces the velocity of the Casson fluid whereas it has different impact in the presence of radiation absorption. Also increasing values of chemical reaction parameter leads to decrease the concentration of the Casson fluid.