Catalytic　complete　oxidation　of　CH4　at　relatively　low　temperatures　is　significant　for　removing　unburned　CH4　from　the　exhaust　of　combustion　engines　fueled　with　natural　gas　or　liquefied　petroleum　gas.　Here　a　nanocomposite　catalyst　(NiO/CeO2)　consisting　of　CeO2　nanorods　and　supported　NiO　nanoclusters　was　prepared　by　a　two-step　wet-chemistry　method.　This　nanocomposite　catalyst　exhibits　high　catalytic　activity　for　the　complete　oxidation　of　CH4　in　the　temperature　range　of　350-600　degrees　C　A　CH3-like　intermediate　bound　to　Ni　cations　was　observed　at　a　relatively　low　temperature　by　ambient　pressure　X-ray　photoelectron　spectroscopy　under　catalytic　conditions.　Parallel　kinetic　studies　of　NiO/SiO2,　CeO2　and　NiO/CeO2　catalysts　show　that　the　apparent　barrier　for　complete　oxidation　of　CH4　on　NiO/CeO2　(69.4　+/-　4　kJ/mol)　is　much　lower　than　the　95.1　+/-　5　kJ/mol　of　pure　CeO2　and　98.4　+/-　5　kJ/mol　of　NiO/SiO2,　supported　by　the　turnover　frequency　of　NiO/CeO2　being　significantly　higher　than　NiO/SiO2　and　CeO2.　These　differences　indicate　a　synergistic　effect　between　the　CeO2　nanorods　and　the　supported　NiO　nanoclusters.　This　synergistic　effect　occurs　at　the　interface　of　NiO　and　CeO2,　observed　in　TEM.　The　lattice　oxygen　atoms　at　the　interface　exhibit　high　activity　based　on　the　lower　reduction　temperature　uncovered　in　studies　of　the　temperature-programmed　reduction　of　H-2.