A novel Mn-Ce/Cu-SSZ-13 catalyst was synthesized for the selective catalytic reduction of NO with NH3 (NH3-SCR) over a wide temperature range. The NOx conversions of this catalyst were above 90% from 125 degrees C to 450 degrees C. The catalyst also possessed good H2O and SO2 resistances at 300 degrees C and possessed higher activities than Cu-SSZ-13 at 80 degrees C to175 degrees C and Mn-Ce at above 200 degrees C. TPD and in situ DRIFTS analyses showed that bridging nitrate groups on Cu-SSZ-13 could not participate in the SCR reaction. Moreover, NH3 was easily adsorbed to form NH4NO3, which encased the surface of the catalyst, thereby blocking the pores and deactivating the active sites. However, for Mn-Ce/Cu-SSZ-13, the bridging nitrates were adsorbed onto the surface and then converted to monodentate nitrates, which acted as the active species for the SCR reaction at low temperature. This phenomenon might be the primary reason for the enhanced SCR performance of Mn-Ce/Cu-SSZ-13 compared with Cu-SSZ-13 at low temperature.