Activities of Cs-loaded MnO x –CeO 2 for combustion of model diesel soot (carbon black) and sorptive NO uptake have been studied. MnO x –CeO 2 is a pseudo-solid solution having redox properties favorable for soot oxidation. The addition of Cs not only lowered the temperature of soot ignition (T i ), but also increased oxidative NO x adsorption to form nitrate on the surface. Soot ignition over Cs–MnO x –CeO 2 was further promoted in a stream of NO/O 2 , presumably because nitrate on the surface plays a role of an oxidizing agent. Soot ignition started just before sharp desorption of NO x , suggesting that adsorbed nitrate species would directly interact with soot.