Water-soluble copolymers of N-acryloyl-N-methylpiperazine and N-acetyl-alpha-aminoacrylic acid were synthesized by radical polymerization. The copolymerization yield ranged between 60 and 97%. The FTIR and NMR spectra demonstrated that the copolymerization occurred. The copolymer composition was determined from H-1-NMR spectra by comparison of methyl groups from both moieties. The copolymers were richest in AAA units. The metal ion retention properties were investigated by the liquid-phase polymer-based retention (LPR) technique at different pH and filtration factors. The affinity for the metal ions depended on the copolymer composition, pH, and filtration factor.