Ternary complexes of Co(II), Ni(II), Cu(II) with N-(2-acetamido)iminodiacetic acid (disodium salt, Na2ADA) and some bi- or tricarboxylic aliphatic acids (succinic, malic, tartaric and citric, H2L or H3L) were prepared. The structure of the complexes was determined by elemental and thermal analyses, IR and electronic spectra as well as conductivity measurements. The general formulas [M(ADA) (L) (H2O)]Na2 (H2O) and [M(ADA) (L)]Na3 (H2O) are deduced for the secondary ligand bi- and tricarboxylate aliphatic acid anions, respectively. An octahedral structure is suggested for the Co(II) and Ni(II) complexes, while a tetragonally distorted structure is proposed for the Cu(II) complexes. Stability constant of the different binary and ternary complexes formed in such system were determined at 25°C and μ=0.1 mol dm-3 KNO3 using the pH-titrimetric technique. It is deduced that the mixed complex is more stable than the corresponding binary aliphatic acid anion complex. The order of stability of the binary or mixed ligand complexes in terms of nature of aliphatic bi- and tricarboxylate anions and metal ion is examined and discussed.