Acrylonitrile (AN)/N-vinylimidazole (VIm) copolymeric hydrogels were synthesized by irradiating their binary mixtures. The AN moieties of copolymers were amidoximated using hydroxylamine hydrochloride in basic medium. The amidoximated hydrogels were used for separating uranyl ions from aqueous solutions by a complexation process. Uranyl ion adsorption studies were conducted from different UO22+ ion solutions (650-1850 ppm). The result of all UO22+ ion adsorption studies complied with the L-type isotherm. The adsorption capacity was found as high as 0.64 g UO22+ g(-1) dry amidoximated copolymer. (C) 2002 Elsevier Science B.V. All rights reserved.