Different compositions of poly(vinylpyrrolidone-co-metliylacrylate) hydrogel, poly(VP-co-MA) were prepared. In the first set, the concentration of the crosslinker, methylenebisacrylamide (MBA) was kept constant while varying the vinylpyrrolidone: methylacrylate ratio, in the second set, the monomers ratio was fixed and the methylenebisacrylamide was changed. The presence of some function groups in the structure of the resultant gel was confirmed using FTIR. The tendency of this copolymer gel to extract different metal ions (Cu2+, Cd2+, and Ni2+) from synthetic wastewater was examined under various conditions such as pH and exposure time. Replacing 20% of the VP with MA causes 11% loss in the equilibrium water content (EWC) and the loss rose to 76% when the MA share in the hydrogel became 40%. Increasing the MBA amount to 1% and 1.5% for the hydrogels prepared using 80% VP leads to 10% and 23% loss in the EWC, respectively. The maximum binding capacity for all the hydrogel samples towards the metal ions under investigation could be reached within 1-2 h and the tendency of the hydrogels to bind Cu2+ is greater than the other metal ions while the Cd2+ removal was the weakest. Increasing the pH from 6.5 to 8 enhances the maximum binding capacity of Cu2+ for H1, H2 (40-50% from the initial metal ion concentration) and this enhancement became more pronounced and reached 65% at pH 8 (H3) despite that this sample acquired the lowest EWC among the prepared hydrogel samples. Increasing the crosslinker concentration from 0.5% to 1% gave better binding for Cu2+ at pH 2-4 and 8 but further increase in the crosslinker concentration from 1% to 1.5% reduced the maximum binding capacity of the hydrogel towards the Cu2+. In contrast, the binding of Cd2+ was improved with increasing the MBA concentration from 1% to 1.5%. Also, increasing the MA as the hydrophobizing monomer in the feed to 40% can increase the preference to Cu2+. The maximum binding capacity of the hydrogel was improved towards all metal ions after regeneration, especially with Cu2+ and Ni2+. (C) 2004 Elsevier B.V. All rights reserved.