Descriptor combinations, consisting of the electrotopological state (E-state) indexes of some skeletal groups, the first-order ¹chi molecular connectivity index and the logarithm of the statistical factor, are employed to describe the second stepwise formation constants of binary and ternary copper(II) complexes with a-aminoacidate ligands. Descriptor sets formed by E-state values of skeletal groups belonging to the chelate rings, ¹chi and the logarithm of the statistical factor lead to the best regression equations. Results suggest that differences in stability over the series of metal chelates depend mainly upon variations in the coordination tendency of the carboxylate ligand groups