In this study, the mesoporous phenyl-silica (PS) is synthesized with tetraethoxysilane (TEOS) and phenyltriethoxysilane (PTES) as the Si-precursors. Then PS is sulfonated by the simple sulfonation with concentrated sulfuric acid to prepare the mesoporous sulfonated-phenyl-silica (SS). The Nafion (R)-based nanocomposite membranes, N/PS and N/SS, are successfully prepared with PS and SS silicas, respectively, and used as PEM for preparation of the PEMFC single cells. It is found that compared with the Nafion (R) membrane, NRE-212, and N/PSs, the best N/SS, SS1, which contains 3 wt.% of SS1 with about 5.18 wt.% sulfonic acid groups, exhibits more than 2-folds higher water uptake and slightly higher ion-exchange capacity (IEC). The highest proton conductivity of the as-prepared nanocomposite membranes at room temperature is in the same order as that of NRE-212. The power density of the PEMFC single cell fabricated with the best N/SS is 460 mW cm(-2) at 110 degrees C under the humidified condition, which is approximately 13% and 53% higher than that with the N/PS and NRE-212. Besides, the peak power density obtained at 65 degrees C under dry condition is 414 mW cm(-2), which is approximately 4 times higher than that of the N/PS. Copyright (C) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.