In this paper, we have studied the combined effects of free convective heat and mass transfer on an unsteady MHD dusty viscous fluid flow in a vertical channel saturated with porous medium subject to the convective boundary condition. The coupled partial differential equations are solved analytically using perturbation technique. The velocity, temperature and concentration fields have been studied for various combinations of physical parameters such as magnetic field, thermal radiation, Biot number and chemical reaction parameters. The expressions for skin friction, Nusselt number and Sherwood number are presented and the results are tabulated. Further, it is observed that the velocity profiles of dusty fluid are higher than the dust particles. © 2017 Published under licence by IOP Publishing Ltd.