We have studied experimentally the effects that the charge adsorbed on the membrane pore walls exerta on the convective diffusion through a porous membrane. The plot of the logarithm of the bulk concentration ratio vs convective flow through the membrane is usually employed to determine the membrane parameter AIL (dfective membrane aredmembrane thickness). It is shown that the deviations from the linear behavior of this plot give us information on the adsorbed charge concentration. A simple model based on the Nernst-Planck equation for the ion fluxes and the Navier-Stokee equation for the pore fluid velocity has proved to be useful for the understanding of the experimental trends observed over a range of membrane pore radius and electrolyte Concentration. Our study can be seen aa an independent confiiation of a rather general result: ion adsorption to the pore walls of inert, porous membranes can significantly affect the transport phenomena, especially in the limit of low electrolyte concentration.