The stability of complex cpmpounds formed from N-(para-substitutedphenyl) glycines(R--NHCH₂COOH, R-CH₃O, CH₃, NO₂, Cl, H) with oopper(Ⅱ), nickol(Ⅱ) and zino(Ⅱ) has been investigated.The stepwise formation constants of these complexes were determined by pH method at 25℃ in 30℃ (volame) ethanol solution in presence of 0.10 M NaClO₄.It was found that some linear free energy relationships exist between the stability of the complex compounds and the basic strengths of the ligands, which may be represented by the following equation: k=CK^-β, where k is the stability constant bf the complex compound and K the dissociation constant of the ligand, and C and β are constants.These relationships are valid under the conditions that only electrostatic effects are present in the system investigated while other factors such as steric or entropy effeotare to be excluded.The effect of lowering dielectric constant of the solvent on the stability of the complex compounds was reflected by the fact that the complexes are more stable in 30% ethanol solution than in water.The order of stability of the complex compounds formed by a givon ligand with Cu(Ⅱ),Ni(Ⅱ) and Zn(Ⅱ) conforms to the Irving order.