Methanol diffusion and electroosmotic drag coefficients for different polymer-electrolyte-membranes have been investigated. It is essential to understand the transport phenomena of water and methanol transport in perfluoro sulfonic acid (PSA) membranes under different methanol concentrations and current densities in order to optimize cell performance and operation. The dependence of the methanol diffusion coefficient as well as the electroosmotic drag coefficient on methanol concentration and current density were observed. ne results are discussed in comparison to measured values obtained by other scientific groups. (c) 2005 Elsevier B.V. All rights reserved.