Potentiometric studies of complexes of Cu (II) and Ni (II) with amino acid (L- isoleucine, Lleucine, L-serine) and chloroquine phosphate (CQ) are conducted in aqueous solution. Change in potential value reflected the formation of complex. Stability constants of the binary and ternary complexes are determined at 35 ± 0.5°C and at ionic strength I = 0.1M KNO3. Titration graphs were plotted between H+ ion concentration and moles of base added. Irving-Rosotti method was applied for calculation of stability constants at each point for binary and ternary complexes. In optimum pH condition, stoichiometric relationship of 1 : 1 metal and CQ binary complex and 1 : 1 : 1 metal : amino acid and CQ ternary complexes are formed. E log K values were also calculated for the system. It indicates greater stabilities of binary complexes over the ternary ones.