Complex formation between end group containing polyacrylamide and BSA has been studied in neutral water. Water soluble and insoluble complexes are formed when divalent copper ions are added to the solution. The contacts between protein and polyelectrolyte are achieved via chelate unit formation in which the copper ion is attached at the center. The solubility of the polycomplexes depends on protein!polymer ratio, Starting with very low concentration of protein in the system, phase separation takes place. Above the critical ratio of the protein/polymer, the mixture again exhibits water soluble character. The velocity of the formation of insoluble ternary complexes has been investigated by spectrophotometric method at different reaction conditions (preparation of mixture, ratio of components, low molecular salts, temperature and stirring, molecular weight of polyelectrolyte and Cu2+ concentration). A hypothetical structural scheme for the formation of soluble and insoluble ternary polycomplexes is proposed.