Taking the NaCl aqueous solution as the working fluid, the mass transfer characteristic of which in a reverse electro-dialysis(RED) stack have been tested under the conditions of changing the current density and concentration difference between solutions through the RED stack. The RED stack used in the experiments was composed of 5 unit membrane cells with Selemion type of ion exchange membranes(IEMs). The results showed that the selectivity coefficient(α), solvent permeability ratio(vw), solute ion transpo...