Unlike common oxovanadium(IV) complexes with tetradentate Schiff base ligands, [N,N′-(2,2-dimethyl-1,3-propylene)bis(salicylideneiminato)]oxovanadium(IV) ([VO(salptn)]) was easily oxidized by dioxygen in aqueous CH3CN. The [VO(salptn)]–O2 stoichiometry was 4:1. This particular reactivity comes from the preference of [VO(salptn)] to be six-coordinate rather than five, that drives the formation of an O2-complex. The structure of the oxidized product, [VO(salptn)]OH, was characterized by single-crystal X-ray diffraction. The results are consistent with a mechanism involving an attack of O2 at the vanadium(IV) center, followed by the formation of the μ-dioxo dimmer as a transient species and the subsequent splitting of the O–O bond by hydrolysis to yield [VO(salptn)]OH.