In this paper, analytical and numerical studies of species separation in vertical and horizontal porous, cylindrical annular cells were presented. The binary fluid, saturating the porous medium, is a water-ethanol mixture. The thickness e, of the horizontal and vertical columns is equal to R o − R i , where R i and R o are respectively the internal and the external radii. H is the height of the vertical cell, and the length of the horizontal cell. Constant temperatures, T hot and T cold , were imposed on the inner and outer cylinders. Since an important species separation, in thermo-gravitational column (TGC), is obtained for e << H, the same assumption was made for the two configurations. The analytical solution was obtained using the parallel flow approximation for both configurations. The governing equations were solved numerically for 2D and 3D configurations using two different softwares (Comsol Multiphysics and a spectral collocation method with Gauss-Lobatto-Chebyshev points). Velocity, temperature, mass fraction fields and time to reach steady state were compared for the two configurations. The amount of species separated at the top or the bottom of each cell was also compared for each configuration.