Polymeric oxaaza macrocycles (PEI-OAM) are constructed on poly(ethylenimine) (PEI) by Ni(II)-template alkylation of PEI with diethyleneglycol ditosylate. The Kf values for Ni(II), Cu(II), and Zn(II) complexes of PEI-OAM are measured at pH 3.5-10 at 25 degrees C. At pH 7, log K-f values for these complexes are 9-15, indicating that the polymeric oxaaza macrocycles can readily reduce concentrations of these metal ions below ppb level. Metal binding ability of nonpolymeric oxaaza macrocyclic compounds reported in the Literature decreases rapidly as pH is lowered below 7, whereas that of PEI-OAM decreases to lesser extents. This is attributed to the electrostatic effects exerted by the ammonium ions of PEI backbone.