Three cationic complexes containing the [(ReO)-O-(V)](3+) core (general formula [ReO(dien-H)(aa)](+), then = diethylenetriamine, aa = glycine, alanine, valine) were studied on polycrystalline Au electrodes employing cyclic voltammetry techniques. The electrochemical behavior of the amino acids (aa) was also evaluated. Experiments were performed at pH 7.0 aqueous solutions at room temperature. The voltammogram of the complex showed current contributions related to the [(ReO)-O-(VI)](4+)/[(ReO)-O-(V)](3+) redox couple, the counterion, and the amino acid ligand.