Galvanostatic oxidation of vanadium was monitored by electron spin resonance (ESR) spectroscopy. Simultaneous observation of the electrode potential together with the ESR intensity revealed that the VO2+ ion concentration increased below the potential of 0.58 V (NHE) by the continuous oxide formation. Above that potential, however, the ESR intensity decreased, indicating further oxidation of VO2+ ion to the higher valent state. The experimental results demonstrate a useful application of ESR to the study of the dissolution of vanadium metal by galvanostatic technique.