The formation of ternary complexes of the Cu(II), Co(II), Ni(II), and Zn(II) metal ions with some hydroxamic acids (acetohydroxamic acid, Aha; benzohydroxamic acid, Bha; salicylhydroxamic acid, Sham; and N-phenylbenzohydroxamic acid, N-PhBha) and some bioligands (alpha-alanine, alpha-ala; L-valine, L-val; norvaline, norval; aspartic acid, aspart; glutamic acid, glut; asparagines, asperg; histamine, Him; and imidazole, imid) was investigated using the potentiometric technique at 25 degrees C and I = 0.10 mol.dm(-3) NaNO(3). The stability constants of these ternary systems were calculated. The order of stability of the ternary complexes in terms of the nature of metal ions, hydroxamic acids, and bioligands was investigated and discussed as well as the values of Delta log K and log X for the ternary systems. The concentration distribution curves of the various binary and ternary complex species in solution were evaluated. The effect of temperature of the medium on both the ionization process of Aha, Sham, aspart, and glut and the complex formation with Cu(II), Co(II), and Ni(II) for 1:1:1 ternary systems in the range of (15 to 45) degrees C and I = 0.10 mol.dm(-3) NaNO(3) in an aqueous medium has been studied. The thermodynamic parameters are calculated and discussed. Evaluation of the effect of ionic strength was carried out in NaNO(3) as a supporting electrolyte I [(0.10 to 0.50) mol.dm(-3)]. The dependence on ionic strength of the stability constants of the binary and ternary complexes was analyzed. In addition, the chelation mode of the ternary complexes was ascertained by conductometric titrations. Also, confirmation of the formation of ternary complexes in aqueous solutions has been done using cyclic voltammetry measurements.