Direct methanol fuel cells (DMFCs) that use a proton exchange membrane (PEM) as electrolyte, is a promising alternative source of energy for the future. However, methanol crossover from the anodic side to the cathodic one is a major problem in DMFC. Proper dispersion of layered silicates within the fuel cell membrane has been proposed as a strategy for improving the barrier properties of the membrane. The validity of this approach has been tested in case of a model membrane consisting of phosphotungstic acid doped poly(vinyl alcohol). A solvent casting technique has been used, which allows the nanofiller to be delaminated by an ultrasonic pre-treatment, as confirmed by TEM and XRD analysis. The layered silicates have a favourable impact on the methanol permeability, whose the decrease overcompensates some loss in ionic conductivity. (c) 2005 Elsevier B.V. All rights reserved.