Naflon((R)) perfluorosulfonic acid polymer electrolyte membranes were uniaxially drawn at a temperature where the alpha-relaxation is active. Polarized UV-Raman spectra revealed the anisotropy developed. They strongly suggest that, upon uniaxial drawing, Nafion macromolecular chains are oriented parallel to the drawing axis, while the perfluorinated side chains exhibit a tendency to be oriented perpendicular to the draw axis. The drawing process resulted in the reduction of the membrane thickness in addition to an enhanced mechanical strength along the draw direction, measured with dynamic mechanical analysis. In a parallel study, a preliminary molecular orientation study of uniaxially drawn Teflon samples allowed a better assignment of the Raman bands of Nafion. (c) 2007 Wiley Periodicals, Inc.