The steady incompressible, viscous, two-dimensional flow of a solution in a channel was considered. The bottom wall was porous and the fins were attached to the top wall. Employing control volume approach, a computer program based on SIMPLE algorithm was developed. Computations were carried out to investigate the effects of the inlet Reynolds number, the fin length, the suction Reynolds number and the slip coefficient on the flow structure and the concentration distribution. It was observed that the thickness of concentration boundary layer increases in the flow direction. The concentration on the porous wall and the concentration boundary layer thickness decrease with increasing fin length, the slip coefficient and the inlet Reynolds number. These results show that fins attached to the upper wall of the channel can be utilized to reduce the concentration polarization and hence improve the effectiveness of the separation process.