Hexagonal boron nitride (hBN) was used as a CuO_X/TiO₂ catalyst carrier and its effect on NO reduction with NH₃ was studied. After hBN was treated with concentrated HNO₃, CuO_X/TiO₂ nanoparticles were dispersed well onto hBN, and the addition of hBN was found to promote NO oxidation, while at the same time suppress NH₃ oxidation to NO, and thus promoted the selective catalytic reduction of NO at reaction temperatures between 150 to 350 °C, and a high de-NO_X efficiency of 90.6% was achieved at 275 °C. Our study indicates that hBN is a promising catalyst promoter and carrier with excellent stability compared to carbonaceous materials.