A novel chelating polymer including three different functional groups, such as amidoxime (-C(NH2)=NOH), azo (-N=N-) and carboxylic acid (-COOH), was synthesized. The poly(acrylamidoxime-co-(1-(2-pirydylazo)-2-naphtyl-2-methacrylate)-co-methacrylicacid) (APM) polymer, prepared in three steps, was characterized by FT-IR and elemental analyses. The resin was used for solid-phase extractive separation and the preconcentration of trace amounts of uranium(VI). The determination of U(VI) was performed by a spectrophotometric method using Arsenazo III as a complexing agent. The optimum conditions were found for the quantitative recovery of U(VI) (pH 5; eluent, 3 mol L-1 HClO4; sample and eluent flow rates, 1 mL min(-1) etc.). The capacity of the APM resin for U(VI) was found to be 24.2 mg g(-1). A preconcentration factor of 37.5 and the three sigma detection limit of 1.6 mu g L-1 (n = 20) were achieved for U(VI) ions. The polymer was used for separating and preconcentrating the uranyl ion existing in seawater samples and a certified reference material (TMDA 70; fortified lake water sample).