The synthesis of methyl mercaptan from COS and H-2 on K+ promoted MoS2 supported on silica is explored. The reaction proceeds via the disproportionation of COS to CO2 and CS2 and the consecutive hydrogenation of CS2 to CH3SH. In parallel to the disproportionation, COS also decomposes to CO and H2S. The characterization of the catalyst by means of XRD, Raman spectroscopy, and adsorption of NO suggests that two active phases, i.e., relatively pure MoS2 and le-decorated MoS2, are present in the sulfided catalyst. The disproportionation of COS and the hydrogenation of CS2 are favored on K+-decorated MoS2; the decomposition of COS to CO is the favored route on pure MoS2. The reaction mechanisms for the decomposition of COS and the hydrogenation of CS2 are discussed. (C) 2011 Published by Elsevier Inc.