The effects of alcohol used as solvent during the sol-gel synthesis of Nafion-SiO2 hybrid electrolytes have been evaluated. The alcohol controls the distribution of silica particles in the phase separated structure of Nafion and both the silica content and the water uptake of hybrid membranes are dependent on the alcohol solvent. Thermal and structural properties inferred from differential scanning calorimetry and small angle X-ray scattering were correlated with the enhanced water uptake and the proton conductivity of hybrid membranes. Accordingly, fuel cell tests carried out at 130 degrees C and low humidity evidenced the superior performance of Nafion-SiO2 hybrids. (C) 2012 Elsevier Ltd. All rights reserved.