The interaction of the VO2+ cation with homocysteine was investigated by electron absorption spectroscopy in aqueous solution at different metal-to-ligand ratios. The direct reduction of vanadate(V) solutions with homocysteine was also investigated. The results suggest that the interaction is different from that found in the case of cysteine and occurs through pairs of amino and carboxylate groups of the amino acid. The interaction of VO2+ with homocystine, the oxidation product of homocysteine, was also analyzed. The interest of the results in relation to vanadium metabolism and detoxification is briefly discussed.