Methanethiol is a necessary ingredient for the synthesis of methyl thioacetate, a presumptive prebiotic precursor of acetyl-CoA central to prebiotic carbon fixation . However, the availability of methanethiol in primordial ocean hydrothermal systems remains unresolved. Methanethiol has been detected in trace amounts in hydrothermal fluids from mid-ocean ridge systems, but has been ascribed to thermal destruction of preexisting organic matter . Although hydrothermal experiments by Heinen and Lauwers synthesized methanethiol from CO2 and hydrogen sulfide (H2S) on iron sulfide (FeS) or metallic iron (Fe 0 ), the yield was much less than 0.1% based on H2S. Loison et al. showed a gas chromatography-mass spectroscopy (GC-MS) evidence of methanethiol formed from carbon monoxide (CO) and H2S in the presence of nickel sulfide (NiS), but no yield was reported.