Electroreduction of a vanadium dinuclear complex [(salen)V-IV-O-V-IV(salen)](2+) in the presence of Or resulted in the stoichiometric formation of a [(salen)V-IV-O-V-V-(salen)=O](+) complex. The process provided not only evidence for the interconversion of vanadium(III)/oxovanadium(V) in the action of vanadium complexes operating as redox catalysts, but also possibilities for the use of the vanadium complex as electrocatalysts for the 4-electron reduction of O-2.