In CO2 reforming of methane over a calcium hydroxyapatite-supported nickel catalyst, the carbon deposition occurred more severely with increase of the methane partial pressure and at temperatures below about 1,000 K. The effects of ceria that was added as a promoter to the nickel catalyst were investigated. It was observed that the ceria not only enhanced the catalyst stability but also increased the activity, and this is considered owing to the oxygen storage capacity of ceria. The TGA analysis demonstrated that the ceria promoted the removal of the deposited carbon. The optimum Ce/Ni mole ratio was ca. 0.3/2.5. The deposited carbon could easily be removed by oxygen treatment at 1,023 K and the catalytic activity could be restored.