Polyelectrolytes of 2-acrylamido-2-methyl-propanesulfonic acid (AMPSA) in the form of crosslinked hydrogels have been obtained. The effect of the amount of crosslinking agent, N,N'-methylene-bis-acrylarnide (BAA), and water content on the conductivity and mechanical properties of the gels obtained was studied and the results were compared with those of poly(AMPSA) aqueous solutions. The highest or values, of the order of 1 S cm(-1) are reached by systems containing 60-80 wt.% of water and 1-2 wt.% BAA. These systems form flexible and transparent membranes. Modification of the mechanical properties of hydrogels consisting in the synthesis of structures of mutually interpenetrating polymer networks of poly(vinylidene fluoride) and poly(vinyl alcohol) (PVA) was performed. The thermal properties of these modified gels were studied. (c) 2006 Elsevier B.V. All rights reserved.