In this work we have brought to the fore the preparation of semi-interpenetrating polymer network by using a crosslinking gaseous reagent. By treating the mixture of poly(vinyl alcohol) (PVA) and a polyelectrolyte (P) as poly(sodium styrene sulfonate) (PSSNa), poly(acid acrylic) (PAA) and poly(1,1-dimethyl-3,5-dimethylenepiperidium chloride) (PDMeDMPCl) with gaseous dibromoethane, we have obtained three ion-exchange membranes which have good physico-chemical properties depending on the preparation and crosslinking conditions. From this study, an increase of exchange capacity and a decrease of the swelling ratio with crosslinking time (or crosslinking rate) was observed. The average capacity was 1.5, 0.8 and 6 mequiv/g for PVA/PSSNa, PVA/PDMeDMPCl and PVA/PAA, respectively. It depended also on the weight fraction of the crosslinkable polymer. The best results were obtained for samples containing 55% PVA and 45% P.