Silica with surface modified with hydrophobic perfluorododecyl groups was used as the additive for perfluorosulfonic acid MF-4SC membranes (Russian analogue of Nation). The hybrid materials were prepared by membranes casting from alcohol polymer solutions contained precursors for the particles formation followed by the hydrolysis of precursors. Membranes with silica concentration ranging from 0 to 10 wt.% and contained silica with various degree of surface modification were investigated. It was found that incorporation of silica with hydrophobic surface results in the decrease of water uptake in comparison with membrane doped with pure SiO2 and initial membrane while conductivity of this membranes is noticeably higher in comparison with membranes doped with pure silica. The maximal conductivity value was observed for MF-4SC membrane doped with 3 wt.% of SiO2 contained 5 mol% of 1 H,1H,2H,2H-perfluorododecyl groups and reaches 0.25 S/sm at 90 degrees C. Explanation of the phenomenon of conductivity increase in membrane doped with silica nanoparticles with hydrophobic surface has been proposed. (C) 2012 Elsevier B.V. All rights reserved.