Rushdi and Simoneit suggested methanethiol as an intermediate of the carbonyl sulfide (CS2)oxalic acid reaction under acidic pH (<0.5), but such reaction was probably rare -if not entirely absent-in the primordial undersea environments. To the best of our knowledge, there is no aqueousphase mechanism demonstrated so far that supports an ample and sustained supply of methanethiol as envisioned in the protometabolism scenario .