Flexible polymer electrolyte membranes consisting of zirconia (titania) and polydimethylsiloxane (PDMS) with the different molecular mass of 4500 and 600 have been synthesized by sol-gel processes. The polymeric membranes showed thermal stability and flexibility up to 300 degreesC due to the presence of cross-linkable inorganic nano-phase in the hybrid macromolecular matrix. The membrane becomes proton conducting polymer electrolyte by addition of 12-phosphotungstic acid (PWA). The conductivity increased up to 7.7 x 10(-2) S/cm through ultrasonic treatment on the membrane, which is in the application level to polymer electrolyte fuel cells. The hybrid materials can be recognized as new, low cost and environment friendly electrolyte membranes. (C) 2004 Elsevier Ltd. All rights reserved.