The formation of binary and ternary complexes of Co(II), Ni(II), and Cu(II) with bicine [N,N-bis(2-hydroxyethyl)glycine] and some selected mono- and dicarboxylic amino acids (glycine, a-alanine, leucine, valine, phenylalanine, asparagine, beta-alanine, aspartic acid, and glutamic acid) was studied potentiometrically at (298.15 +/- 0.1) K and I = 0.1 mol(.)dm(-3) (NaNO3) in aqueous solution. The acid-base properties of ligands were investigated and discussed. The formation of the 1: 1 binary and 1: 1: 1 ternary complexes is inferred from the corresponding titration curves. The acidity constants of the ligands were determined and used for determining the stability constants of the complexes formed under the experimental conditions. The ternary complexes are formed in a stepwise mechanism. The stability constants of the binary and ternary systems were evaluated. The stability of the ternary complexes is also discussed in relation to that of the binary complexes of secondary ligands. An evaluation of the effects of ionic strength and temperature of the medium on the stability of the ternary system Cu(II) + bicine + amino acids has been studied. The thermodynamic parameters were calculated and discussed. The stability constant of the above-mentioned ternary system has been investigated in a dioxane-water solution. The complexation behavior of the ternary complexes was ascertained using differential pulse polarography (DPP) and square wave voltammetry.