The ammonia-SCR catalytic activity of unsupported CeVO4 with an excess of CeO2 was investigated in standard and fast-SCR conditions. Solids were obtained from a hydrothermal synthesis route under a mild condition and then stabilized after aging in a wet atmosphere at 600 and 850 °C. Particular attention was paid to the role of excess CeO2 and the consequences of hydrothermal aging on physical–chemical properties and catalytic activity. The XRD patterns put into evidence the formation of the zircon-type structure of CeVO4 in agreement with a segregation of cubic face-centered structure of ceria (CeO2). Along with adding an excess of CeO2, high specific surface area (102 m2/g) for the 11wt% CeO2/CeVO4 solid was obtained. The presence of CeO2 nanoparticles in addition to CeVO4 nanoparticles have limited the decrease in the specific surface area after aging at 600 and 850 °C. The catalyst with 11wt% CeO2/CeVO4 exhibited the best catalytic performances in standard and fast SCR conditions after thermal aging at 600 °C.