This paper investigates the combined effects of magnetohydrodynamics and radiation on free convection flow past an impulsively started isothermal vertical plate with Rosseland diffusion approximation. The fluid considered is a gray, absorbingemitting radiation but a non-scattering medium, with approximate transformations the boundary layer governing the flow are reduced to non-dimensional equations valid in the free convection regime. The dimensionless governing equations are solved by the finite element method.