New proton exchange membranes have been obtained by the thermal copolymerisation of styrene and divinylbenzene inside polyvinylidene fluoride (PVDF) films followed by sulphonation. The content of incorporated cross-linked polystyrene moieties and the ion exchange capacity (IEC) values of the membranes reach 50 wt% and 2 mmol/g, correspondingly, under the proposed approach. It was found that the dependency of the membrane proton conductivity on the IEC values has a threshold character. This fact indicates that the cross-linked sulphonated polystyrene (CSPS) phase has a micro-heterogeneous distribution across the membrane section. The main feature of the obtained membranes is low methanol uptake. It was found that the membrane with IEC similar to 2 mmol/g sorbs approximately 45 wt.% of water and only 30 wt.% of methanol. The synthesised membranes were tested in both hydrogen and direct methanol fuel cells (DMFC). The highest power density of 130155 mW/cm(2) in the hydrogen fuel cell was found for the PVDF-CSPS membrane, which exceeds the corresponding value for a Nafion-115 cell (approximately 100 mW/cm(2)). The characteristics of DMFCs are similar to both the PVDF-CSPS and Nafion-115 membranes. (C) 2013 Published by Elsevier B.V.