Copolymers derived from the binary mixture of N-vinyl imidazole (VIm) and Acrylonitrile (AN) monomers have been synthesized by the irradiation of their solution with Co-60-gamma rays. Gelation percent-dose graphs were formed, and 80% of gelation (maximum percentage) has been reached at around 14 kGy dose. To impart metal ion adsorption properties, the hydrogels were amidoximated by the reaction of cyano groups on AN with hydroxylamine in aqueous media. Swelling behaviors of hydrogels were investigated before and after amidoximation. Hydrogels had 54% of swelling originally, this ratio reached 220% of swelling after amidoximation. The degree of amidoximation was followed by FT-IR spectroscopy. The structures of copolymers were analyzed spectroscopically and thermally before and after the amidoximation reaction. (C) 2000 Elsevier Science Ltd. All rights reserved.