A binary catalyst of CaO-ZnO is effective for the selective conversion of CH4 to C-2 hydrocarbons using CO2 as the oxidant. C-2 selectivity approaches 80% with a Ct yield of 4.3% over the catalyst with a Ca/Zn ratio of 0.5 at 875 degrees C. The lattice oxygen of the CaO-ZnO converts CH4 mainly to H-2 and CO. The presence of CO2 forms a new oxygen species, which is active and selective for the conversion of CH4 to C-2 hydrocarbons. The CaO component in the catalyst enhances the adsorption of CO2 and thus suppresses the reaction involving the lattice oxygen. The reduced Zn site is suggested to activate CO2.