A series of proton conducting composite membranes based on Nafion (R) and 9P(2)O(5)-6TiO(2)-85SiO(2) glass were prepared by the solution-cast method. Infrared (IR) spectroscopy and X-ray diffraction (XRD) spectrophotometer were employed for structural analysis of both 9P(2)O(5)-6TiO(2)-85SiO(2)- and 9P(2)O(5)-6TiO(2)-85SiO(2)-filled composite membranes. The effect of the filler on membrane properties was examined. As it offers not only a new proton conductive path associated with the increased proton carrier concentration, but also an increase in glassy regimes, it resulted in enhancement of proton conductivity, water uptake, and mechanical stability: however though, a reduction in methanol permeability. These properties were also affected by the membrane cleaning process, whereby the conductivity of the cleaned membrane with 3 wt.% gel content, 1.05 x 10(-2) S/cm, was much higher than that of the non-cleaned at the same gel content, 0.5 x 10(-2) S/cm. (C) 2010 Elsevier B.V. All rights reserved.