The influence on the substitution of the cationic form of a Nafion (R) 117 membrane was investigated by means of swelling and permeation measurements. This effect was studied in terms of the permeability and the solubility of a mixture of methanol and water through membranes substituted by Li+, Na+, K+ Rb+ and Cs+. It was found that both, permeability and solubility decrease with increasing the ionic radius of the substituted cation. The dependence of permeability and solubility on the temperature was studied by measurements at different temperatures. This allowed to determine the activation energy of permeation and the enthalpy of sorption by numerical fitting of experimental data. The trend in activation energy of permeation and the enthalpy of sorption did not appear to be related to the ionic radius of the cation. The increase of differences in permeability of the different cation forms, when the temperature was increased, has been related with the results obtained for solubility. (C) 2015 Elsevier B.V. All rights reserved.