NOx(NO, NO₂) was reduced by propene over an anatase precursor of titania supported indium catalyst. The support titania(TiO₂-SG), which prepared by sol-gel method, showed higher effciency than commercial titania(TiO₂-Ref)when it supported indium. For the activity of In/TiO₂ catalyst were changed with indium loading content, have been found to be improved by the loading contents, and was the highest at 5 wt %(623 K);66%, 2 wt %(673 K);51% in NO reduction. Furthemore, the activity of In/TiO₂-SG catalyst was enhancemented about 10∼20% in NOx conversion, when the impregnated method of indium sol-gel titania hydrate phase[In/TiO₂-SG(OH)] was used.