Generally, low C/O ratios have higher CH 4 conversion and synthesis gas yields. At higher C/O ratios the selectivity between partial and full oxidation depends more strongly on the metal (Supporting Information Figures and). The highest synthesis gas yield was observed at C/O = 0.8 on a metal with ∆E C = -6.75 eV and ∆E O = -5.0 eV. This C/O ratio coincides closely with the highest synthesis gas exit selectivities on Rh(111). Sensitivity analyses will show why there are significant drops in yields and conversions that lead to a volcano plot as well as why there is a preference switch between full and partial oxidation as metal properties change.