Electrochemical characterization of three cellophane membranes with different content of regenerated cellulose was carried out by determining salt diffusion and ion transport numbers, which were obtained from diffusion and membrane potential measurements carried out with the membranes in contact with NaCl solutions at different concentrations. Results show a decrease for salt permeability with the increase of cellulose content in the membranes, which can be related with the decrease in the swelling degree of the samples containing higher amount of cellulose, while a slightly increase in the cation transport number was obtained. The effect of gamma-irradiation in structural and electrochemical parameters of these membranes was also studied. Two different radiation doses (10J/kg and 80J/kg) were used, which were delivered by a (CO)-C-60 Cobalt Unit. Changes in membrane permeability, cation and water transport numbers were obtained in order to determine structural and electrical modifications in the membrane matrix as a result of irradiation. According to the experimental results, gamma-radiation produces: (i) a reduction in salt permeability, which strongly depends on the membrane cellulose content (between 20% and 40% for 10J/kg dose), but much lower reduction exist when the two different radiation doses for a given sample are compared; (ii) a slight increase in the negative character of cellophane membranes independently of the cellulose content. (c) 2005 Elsevier B.V. All rights reserved.