In the present work, the oxidation behavior of oxalic acid with NH₄VO₃ was examined via cyclic voltammetry in KCl aqueous solution. The cyclic voltammetry gave a reversible redox couple of waves for NH₄VO₃ in the absence and presence of  oxalic acid due to the reduction effect of +5 vanadium ion to +4 one. Also, the oxidation effect was discussed by the oxidation peak in the reverse direction. The positive shift in the potential of both the oxidation and reduction peaks of NH₄VO₃ in the presence of oxalic acid supports the oxidation mechanism. The oxidation stability constants and Gibbs free energies of oxidation resulting from the interaction of NH₄VO₃ on oxalic acid were evaluated and their data were discussed.