The present paper is devoted to the properties of sulfonated cation-exchange membranes obtained by radiation chemical grafting polymerization of styrene with divinylbenzene on a polyethylene film. The mechanical and transport properties (conductivity, diffusion permeability, and transport numbers) of the membranes obtained with various amounts of a cross-linking agent (0-3.5%) and degrees of polystyrene grafting (23-32%) were investigated in comparison with commercially available membranes, i.e. Nafion (R) 117 and Neosepta (R) CMX. Tensile strength values around 15-20 MPa were obtained, and they increased with increasing cross-linker amounts. The conductivity of membranes containing no cross-linking agent reached 8.4.10-2 Omega(-1) cm(-1) at 25 degrees C and high relative humidity. As the amount of the cross-linking agent increased, the water uptake in membranes and their conductivity at high relative humidity decreased, whereas the activation energy of conductivity increased. At low humidity (RH=30%), the water uptake and conductivity increased with increasing amounts of the cross-linking agent. The membranes based on cross-linked polystyrene had low diffusion permeability, while the associated cation transport numbers were higher than those with commercial Nafion (R) 117 membrane. The calculated theoretical power of reverse electrodialysis batteries based on the best membranes was 10% higher than that of the battery based on the Neosepta (R) CMX membrane. (C) 2016 Elsevier B.V. All rights reserved.