Several oxovanadium (IV) complexes of pyradoxamine (PM), pyridoxol (P), pyridoxal (PL), and glycinehydroxamate (GX) were obtained as a result of potentiometric data analysis using SUPERQUAD at I = 0.15 M NaCl and T = 25°C. Protonated, unprotonated and hydroxospecies were detected in solutions. No polymeric species of oxovanadium(IV) were found under the experimental conditions used. Differential pulse polarography (DPP) was used to study the reduction properties of VO 2+ complex species. Electronic spectra of the systems were discussed. Structures of some complex species of the vanadyl ions were suggested based on the knowledge of the ligating atoms provided by the ligands as well as the assumption that the metal ion can acquire at least an octahedral geometry. The uptake of these species in biological systems was also discussed.