The effect of heat source/sink on free-convective mass transfer flow past an accelerated infinite vertical plate in the presence of transverse magnetic field is investigated. Laplace transformation technique is used to find the exact solution of the problem. The profile of temperature, concentration, and velocity are shown graphically for magnetic field parameter, Prandlt number, Heat source/sink parameter, Thermal Grashof number, Mass Grashof number, and Schmidt number. Variations of Skin-friction, Nusselt number, and Sherwood number are also discussed with the help of graphs. It is shown that velocity of the fluid increases with increase value of Schmidt number and magnetic field parameter. Velocity of fluid decreases with increasing time, heat source/sink parameter, thermal Grashof number, mass Grashof number, and Prandlt number. It is also shown that mass diffusion increases the species concentration. Further, the study concludes that the skin friction coefficient decreases with increased heat source/sink parameter.