In this paper an exact analysis to study the combined effects of thermal diffusion (Soret) and heat generation on a mixed convection flow past an infinite vertical porous plate in presence of thermal radiation has been made. The governing system of partial differential equations subject to favorable boundary conditions is being solved analytically. CoglyVincentine-Gilles equilibrium approximations have been used to describe the radiative heat flux in the energy equation. Closed form of solutions for the velocity field, the temperature field and the concentration field are obtained and discussed graphically for various values of the physical parameters such as radiation parameter, Soret number, Grashof number, modified Grashof number, Prandtl number, Schmidt number and heat generation parameter. Moreover, expressions for the skin-friction, heat transfer co-efficient and mass transfer co-efficient are discussed with graphs and tables.