||We have studied supported V2O5-based catalysts with different vanadate structures to simultaneously conduct selective reduction of NO by NH3 and oxidation of gas-phase mercury. The catalysts were prepared by a wet impregnation technique using different supports, such as anatase- and rutile-type TiO2, SiO2, and TiO2-SiO2. 51V NMR measurements disclosed that tetrahedral and octahedral coordination environments of VOx depend not only on the support but also on VOx amount. This was consistent with Raman spectra for the supported V2O5-based catalysts. These catalytic activities for the NO reduction with NH3 strongly vary with the support, and this observation could be explained by an amount of and a thermal stability of NH3 adsorbed on each sample. The extent of the oxidation of elemental mercury vapor at chosen temperatures was associated with the VOx structures.