Poly(N-vinyl 2-pyrrolidone) (PVP)/acrylonitrile (AN) interpenetrating polymer networks (IPNs) were synthesized and amidoximated for the purpose of uranyl ion adsorption. The adsorption of amidoximated IPNs was studied from different uranyl ion solutions (850, 1000, 1200, 1400, and 1600 ppm). The result of all our adsorption studies showed that the bonding between UO22+-amidoxime groups complied with the Langmuir-type isotherm. The adsorption capacity was found as 0.75 g UO22+/g dry amidoximated IPN. In order to increase the UO22+ ion adsorption capacity the amidoximated IPN was treated with alkali, but no significant increase could be observed. (C) 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2324-2329, 2001.