Recently there has been a renewed interest in Co-catalyzed Fischer- Tropsch synthesis (FTS) from natural gas, coal, and biomass, because it offers a realistic alternative to crude oil as a source of transportation fuels. Efforts to understand the FT mechanism on the atomic level have mainly focused on theoretical methods, whereas experimental surface science results have only had little impact on the understanding of the mechanism. An essential step in any FT mechanism is scission of the C-O bond. On a flat Co(0001) surface direct dissociation of the CO molecule is practically impossible at FTS conditions. We have found for the first time experimentally that the C-O bond can be broken at 350 K even on the relatively inert Co(0001) surface if a CxHy group and a hydrogen atom are attached to the C-end of the C-O moiety.