Using C-13 and C-13(H-1) NMR spectroscopy, structure and reactivity of vanadium peroxo complexes formed in the catalytic system [VO(Oi-Pr)3]/Schiff base ligand/H2O2 for enantioselective oxidation of sulfides were concerned. It was shown, that two types of monoperoxo vanadium(V) species bearing one Schiff base ligand per vanadium atom predominated in this catalytic system at low temperature. These complexes are unstable at room temperature and decompose with half-life time of 20 min. The rate of this decomposition markedly increases in the presence of methyl phenyl sulfide. Addition of a fresh portion of H2O2 restores partially the peroxo vanadium intermediates. These data suggest that the peroxo vanadium species observed could be the active intermediates in enantioselective oxidation of sulfides. Two types of peroxo complexes found, probably, differ in the mode of Schiff base ligand coordination.