We report the behaviour of a silica-supported Pd-Zn catalyst in the hydrogenation of CO (total pressure=20 bar, T=548-598 K). Unusual high selectivity to higher hydrocarbons and higher oxygenated products (ethanol and acetaldehyde) was observed. An in-situ DRIFT study under reaction conditions, with analysis by mass spectrometry of products evolved, was carried out. The presence of surface acetate species is related to the production of acetaldehyde, which is proposed to be the primary C-2-oxygenated product.