In this study, the correlation between surface vanadium species and reactive lattice oxygen in the selective catalytic reduction of NOx by NH3 was investigated. The properties of the V/TiO2 catalysts were investigated using physicochemical measurements, including Brunauer-Emmett-Teller surface area, temperature programmed reduction with hydrogen, Raman spectroscopy, and UV-visible diffuse reflectance spectroscopy. V/TiO2 catalysts were prepared using the wet impregnation method by supporting 2 wt% vanadium on TiO2 thermally treated at various calcination temperatures. Lattice oxygen participating in the reaction was found to be most abundant in 2V/TiO2-600, prepared from TiO2 calcined at 600 degrees C. An increase in reactive lattice oxygen, resulting from an increase in the proportion of polymeric distorted tetrahedral structure existing on the surface of the catalyst, improved the catalyst efficiency. A polymeric distorted tetrahedral structure is referred to as a bridged bond (V-O-V). In addition, greater SO2 resistance was related to a higher polymeric VOx ratio. Thus, the bridged bond (V-O-V) provides the lattice oxygen participating in the reaction.