A theoretical model is proposed to predict Darcy-scale mass transport in porous media coupled with non-equilibrium heat transfer and taking into account the thermal diffusion process. A volume-averaging technique was used with approximations leading to a two-equation or two-temperature model for the macro-scale energy balance equations. Because of Soret effect, the concentration deviation with respect to the averaged value is a function of concentration and temperature gradients in the fluid phase, the temperature gradient in the solid phase, and the difference between the two averaged temperatures. The mapping between deviations and averages involves four closure problems for the mass transport equations: problems which were solved numerically over a two-dimensional periodic-unit cell for evaluation purposes. The results show that the effective coefficients depend strongly on the thermo-physical properties of the medium and the Péclet number. In particular, the effective-Soret coefficient in porous media changes with the Péclet number and the phases thermal conductivity ratio.