The unprecedented combination of sulfur removal and selective oxygen addition is observed in the formation of acetone from 2-propanethiol on Rh(111)-p(2 X 1)-O. The reaction is studied by temperature programmed reaction spectroscopy, and acetone is identified on the basis of the mass spectrometer intensity distribution. Propene elimination via C-S bond scission and selective beta-hydrogen elimination also occurs. 2-propyl thiolate forms upon adsorption at similar to 100 K and the reaction is proposed to proceed via 2-propyl. beta-hydrogen elimination from 2-propyl would yield propene, while oxygen addition would afford 2-propoxide which readily forms acetone. The competing combustion process proceeds via an undetermined pathway. These reactions offer insight into the control of selective C-H bond activation by oxygen on Rh(111) which has broad significance in oxidation chemistry.