The catalyst deactivation behavior of rhodium-coated foam monolith was systematically investigated in order to understand the means to improve the durability of the rhodium catalyst applied for catalytic partial oxidation of methane (CPOM). The overall CPOM reactions on the foam structured catalyst have been acknowledged to take place first in an oxidation zone and thereafter in a reforming zone. Severe metal sintering near the entrance of the structured catalyst (i.e., in the oxidation zone) was identified to be responsible for the observed deactivation of rhodium catalyst in the course of a 1000 h time-on-stream test under quasi-adiabatic conditions. Further analyses on the deactivation process indicated that the reaction pathway in the oxidation zone near the entrance can be summarized by a mixed mechanism, that is, two oxidation reactions and one reforming reaction, where H, is the indirect product of steam reforming of the unreacted CH4. Detailed studies on the dependence of the catalyst stability on the operating conditions and the catalyst designs showed that adding an inert gas to the reactant gases, increasing the metal loading and/or decreasing the pore size of the foam-structured catalyst in the oxidation Zone, can improve the catalyst stability, while the catalyst modifications in the reforming zone has little effect on the overall behavior of the catalyst stability.