This study investigates the influence of different operating parameters in the transport of water and methanol through a Nafion membrane when it is used to separate water from a methanol-water solution. For this purpose, measurements of mass flux and concentration change have been performed at different values of circulation velocity, concentration of the methanol-water solutions and temperature conditions. From the experimental data, the water and methanol partial fluxes have been estimated, and it was found that the water flux is always lower than the methanol flux, but it cannot be neglected. Whereas total and methanol fluxes seem to have predictable and similar behaviors, the water flux seems to be less predictable and it exhibits a very distinct behavior. Methanol and water permeabilities have been calculated, and from these values the activation energy of methanol and water fluxes in the membrane has been estimated. The results have been discussed in terms of the methanol and water solubilities in the membrane. (C) 2009 Elsevier B.V. All rights reserved.