A 10% La2O3 supported on fused MgO (periclase) catalyst has been studied in the 0.45-3.04 atm range for methane partial oxidation to ethane plus ethylene. X-ray diffraction showed that this catalyst, operated by a mechanism La2O3-->2La(3+)O(2-)e(-)+[0], provides active oxygen and vacancies e(-) for the surface reaction.Four independent reactions were found that allowed calculation of the rates and approximate kinetics of every species in the reacting system : 2CH(4) + 1/20(2) --> C2H6 + H2O; C2H6 + 1/20(2) --> C2H4 + H2O; 2CH(4) + 3O(2) --> 2CO + 4H(2)O; 2CO + 2H(2)O reversible arrow 2CO(2) + 2H(2). The equilibrium proceeds so fast that it is not possible to distinguish whether CO or CO2 is the primary product. It was found that oxygen conversion was in a transition regime between surface reaction and mass-transport control in the 700-825 degrees C range. Oxygen conversion is strictly transport controlled at 850-875 degrees C while methane reaction rate remains surface controlled. It is in this oxygen-transport controlled regime at 875 degrees C that our highest yield of 16.2 mol% C-2 was obtained. We have fitted kinetics in both transition- and transport-controlled regimes.Finally, it should be noted that catalyst surface temperatures were calculated to be far above than those of the bulk gas temperatures as a consequence of the transport control; as much as 222 degrees C temperature rise at 875 degrees C gas temperature was observed.