The problem of unsteady mixed convection from impermeable vertical flat plate in a fluid saturated porous medium incorporating the variation of permeability and thermal diffusivity is analyzed.The similarity solutions are obtained for the problem using scaling group of transformations.Furthermore the similarity equations are solved numerically by employing Kellr-Box method.Numerical results of the local skin friction coefficient and the local Nusselt number as well as the velocity profile are presented for different physical parameters.