The　partial　oxidation　of　methane　to　dimethyl　ether　(DME)　was　studied　on　palladium　supported　on　SiO2　,　SiO2-ZrO2　,　and　ZrO2　at　225-375　degrees　C　and　0.1　MPa　using　either　O-2　or　a　mixture　of　NO　and　O(2　)as　the　oxidants.　The　NO　+　O-2　mixture　was　more　reactive　than　the　O-2　toward　methane,　probably　due　to　the　formation　of　active　surface　nitrate　species.　The　formation　of　DME　on　the　catalysts　was　influenced　by　the　support,　with　the　Pd/ZrO2　catalyst　producing　DME　and　the　Pd/　SiO2　catalyst　producing　only　CO2　,　irrespective　of　the　oxidant　used.　The　Pd/SiZrO2　catalyst　formed　DME　only　when　O2　alone　was　used　as　the　oxidant.　For　the　reaction　with　NO　+　O-2　,　in　situ　Fourier　transform　infrared　(FTIR)　measurements　showed　that　the　partial　oxidation　activity　on　Pd/ZrO2　was　related　to　its　ability　to　form　surface-bridged　nitrate　species,　likely　due　to　the　presence　of　basic　sites.　However,　an　inhibitory　effect　of　basicity　on　CH4　turnover　frequency　(TOF)　was　attributed　to　surface　nitrate-induced　structural　modification　deduced　from　X-ray　absorption　fine　structure　spectroscopy　measurements.　For　the　reaction　with　only　O-2　,　the　formation　of　DME　over　Pd/ZrO2　and　Pd/SiZrO(2　)was　attributed　to　the　reported　ability　of　ZrO2　to　retain　methoxy　intermediates.　Furthermore,　a　weak　structural　effect　on　the　TOF　observed　with　O-2　was　attributed　to　competing　effects　of　decreasing　activity　for　C-H　activation　and　increasing　resistance　to　Pd　oxidation　with　increasing　particle　size.