Self-assembled Nafion-SiO2 polymerelectrolyte membrane enhanced by ePTFE matrix was prepared in this study. The original ePTFE membrane was chemically modified before the preparation by sodium-naphthalene treatment to increase the wetting compatibility between self-assembled Nafion-SiO2 dispersions and ePTFE matrix. Compared to the freestanding Nafion-SiO2 membrane, the physical strength of the as-resulting ePTFE PEM was significantly improved from similar to 20 MPa to 32 MPa. The area conductance of the as-resulting membrane was also promoted to similar to 40 S cm(-2) and similar to 50 S cm(-2), respectively at 60 degrees C and 100 degrees C with the decrease of the membrane thickness (15 mu m) in 50% RH gas atmosphere. With the presence of self-assembled silica particles, the self-assembled Nafion-SiO2-ePTFE composite membrane possesses excellent water-retention property. At elevated operating temperature of 100 degrees C, 50% RH, 0 back pressure, the output voltage of the Nafion-SiO2-ePTFE fuel cell was 0.603 V under condition of 600 mA cm(-2), 0.105 V higher than that of the freestanding Nafion/ePTFE fuel cell under the same condition. (C) 2007 Elsevier B.V. All rights reserved.