Solvent uptake, hydraulic and electroosmotic permeabilities, true cation transport number, effective fixed charge concentration, and limiting current values have been determined in aqueous LiCl solutions for three commercial cation-exchange membranes with different morphologies and similar electric properties. The differences found in the equilibrium and transport properties of the membranes have been analyzed on the basis of their different structures. The experimental results show that the membrane Morphology has an influence oil the effect that the presence of an electrolyte has in the solvent uptake and in the liquid permeation. Differences have also been found in the polarization concentration effects, and on the loss of the membrane selectivity with the increase of the electrolyte concentration. (C) 2009 Elsevier Inc. All rights reserved.