The speciation of the ternary VO2+- 1,10′-Phenanthroline (Phen, L) and VO2+- 2,2′-Bipyridine (Bipy, L) complexes with the amino acids: Glycine (Gly, HB), α-Alanine (α-Ala, HB), β-Alanine (β-Ala, HB), Serine (Ser, HB), Threonine (Thr, HB), Leucine (Leu, HB), Isoleucine (Ile, HB), Valine (Val, HB), Tryptophan (Thr, HB), Glutamine (Gln, HB), Methionine (Met, HB) and Phenylalanine (Phe, HB) were obtained via potentiometric titrations done at 25°C using 1.0 mol.dm-3 NaCl as the ionic medium.The anal. of the exptl. data were done with the program LETAGROP, and the HYSS program was used to obtain the distribution diagrams.Related stability parameters including δ log10K, log10X and % R.S were determined only for the Bipy.In the case of the Phen these parameters could not be obtained because the complex [VO(L)(B)]+ was not detected with this ligand.