Catalytic effectiveness for the synthesis of ethane and ethylene from methane and carbon dioxide has been examined mainly at 1123 K over 14 lanthanide oxides. Praseodymium (Pr) and terbium oxides show high yield and high selectivity of C-2 hydrocarbons among lanthanide oxides. The catalytic performances of Pr oxides are influenced by the preparation method; a commercial Pr oxide prepared from the oxalate shows the highest C-2 selectivity of about 50%, and the stable performance for 20 h. Higher partial pressures of CO2 and CH4 are favorable for C-2 formation over the oxide catalyst. Reaction mechanisms over Pr oxides are discussed in terms of a redox mechanism involving the unstable lattice oxygen.