In this study a novel oxo-diperoxo tungsten(VI) complex [WO(O2)2(phox)] was prepared by reaction of WO3 in H2O2 with oxazine-type ligand, 2-(2′-hydroxyphenyl)-5,6-dihydro-1,3-oxazine (Hphox). The complex was characterized by FTIR, 1H NMR and elemental analysis. The single-crystal X-ray diffraction studies revealed a seven coordinate tungsten center with a distorted octahedral geometry. The [WO(O2)2(phox)] complex was applied as a catalyst in efficient, and selective oxidation of sulfide to sulfoxide using 30% H2O2 or UHP as oxidants. This catalyst showed excellent catalytic activities and high selectivities in producing a variety of aryl and alkyl sulfoxides under mild conditions. To get...