The chlorination of cerium dioxide was studied by thermogravimetry under controlled atmosphere between 800 and 950 degreesC. An apparent activation energy of 190 kJ mol(-1) was observed. To discriminate the effect of the vaporization of the CeCl3 on the chlorination rate, this process was also studied with the same technique between 850 and 950 degreesC. An apparent activation energy of 184 kJ mol(-1) was determined. The CeO2 chlorination rate was found to be under a chemical-mixed control influenced by the vaporization of CeCl3.