The magnetohydrodynamic flow of a viscous incompressible fluid past an infinite vertical plate surrounded by a porous medium has been analytically investigated during natural convection. The heat and mass transfer characteristics are examined in the presence of heat generation, chemical reaction, thermal radiation, and Soret effect. An oscillating temperature of the plate is considered about a constant mean temperature. The Laplace transform technique is applied to solve the governing system of coupled partial differential equations. The concentration, velocity, penetration distance, skin-friction, Nusselt number, and Sherwood number results are obtained from the solutions and thoroughly discussed. The results exhibit that the velocity and the penetration distance enhance with an increase in Soret number, whereas the skin-friction decreases with increasing Soret number. The heat transfer rate enhances with the escalation of radiation parameter but diminishes with the increase of phase angle. It is also seen that the rate of mass transfer is occurring from fluid to the plate surface in the presence of Soret effect and surface temperature oscillations. © 2020, Akadémiai Kiadó, Budapest, Hungary.