Ionophoretic technique has been used to study the equilibria in simple and mixed lig and systems in solutions. For the study of ternary complexes the concentration of Resorcinol was kept constant in the case of Metal-Resorcinol –Tyrosine complex whereas tyrosine concentration is kept constant in case of Metal –Tyrosine –Resorcinol complex while that of secondary ligand tyrosine/Resorcinol is varied. The stability constant of Co(II)-Resorcinol, Co(II)-Tyrosine (1:1), Co(II)-Tyrosine (1:2), Co(II)-Resorcinol-Tyrosine and Co(II)-Tyrosine-Resorcinol complexes have been found to be 1012.96, 1016.21, 10 9.60, 108.20 and 106.54 respectively at 0.1M (HClO4) and 250C.