It was found that the formation constants (K) of CuX(QPVP)n− (X = ethylenediaminetetraacetate ion (edta) and N-(2-hydroxyethyl)ethylenediamine-N,N′,N′,-triacetate ion (hedta), QPVP = partially quarternized poly(4-vinylpyridine)) increase sharply with increasing degree of quarternization (Q) of QPVP. In the Cu(edta)2−/QPVP system. K values are 481.mol−1 for Q = 0%, 8701.mol−1, for Q = 25%, and 1,1.103l.mol−1 for Q = 61%, in aqueous methanol (volume ratio 1:1) at μ = 0,1 mol.l−1, pH = 8,0. and T = 25°C. In the system CH3Co(dmg)2H2O/QPVP, K decreases linearly with increasing degree of quarternization of QPVP from K = 1,7.103l.mol−1 for Q = 0% to K = 95l.mol−1 for Q = 61% in aqueous methanol (volume ratio 3:7) at μ = 0,05, pH = 8,0, and T = 25°C. The decrease in K is +scribed to a relatively large decrease in the rate constant of the forward reaction and a small increase in that of the backward reaction.