The formation constants of binary and ternary complexes of Schiff bases MEMIIMP, MIIMP, BMIIMP, CMIIMP, MMIIMP, MIIBD and some N,O; N,N; O,O donor ligands with Co (II), Ni (II), Cu (II) and Zn (II) have been determined by potentiometrically at 0.1M KNO3.in aqua organic medium. The effects of temperature and ionic strengths on binary systems have been studied. All these metalions form 1:1 and 1:2 binary complexes and 1:1:1 ternary complex. The thermodynamic parameters ΔG, ΔH and ΔS of binary complexes have been determined and discussed. The stabilities of ternary complexes are discussed on the basis of Δlog K.