Three different morphologies of CeO2 supports (NP, NC, and NR) were prepared by hydrothermal method and further Mn2O3 is impregnated on CeO2 supports using wet-impregnation methods, and their activity for NO reduction using NH3-SCR technique is analysed. The prepared catalysts and supports are further characterized through scanning electron microscopy (SEM), Energy-dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD), X-ray Photoelectron Spectroscopy (XPS), and transmission electron microscopy (TEM), and Brunauer–Emmett–Teller (BET). The catalytic performance of Mn2O3/CeO2-NP has shown the highest conversion (76.06 %) compared to the other two catalysts in the temperature range of 50 - 450°C.