We have previously reported that copper-cobalt catalysts supported on MgO, La2O3, CeO2, TiO2, ZrO2 and SiO2 exhibit different catalytic behaviours for the formation of higher alcohols in the CO + H-2 reaction. These catalysts were characterised by complementary techniques. The extent of reduction of the copper-cobalt phase studied by magnetic measurements and X-ray photoelectron spectroscopy (XPS), varied with the nature of support; the presence of copper enhanced the reducibility of cobalt on MgO and SiO2. From XPS results, and those deduced from Fourier transform infrared and ethane hydrogenolysis, it is concluded that no formation of a superficial Cu-Co alloy occurred during, or after, reduction by hydrogen.