Novel catalysts for the selective production of higher alcohols from syngas could offer improved pathways towards synthetic fuels and chemicals. Cobalt–copper alloy catalysts have shown promising results for this reaction. To improve control over particle properties, a liquid phase nanoparticle synthesis based on the polyol method was selected to synthesize Co2.5Cu particles, which were then supported onto a variety of metal oxide supports (Al2O3, SiO2, TiO2, ZrO2). The catalysts were characterized by transmission electron microscopy, X-ray diffraction, and X-ray photoelectron spectroscopy before and after catalytic testing in a flow reactor at 250 °C and 40 bar. The results show alloyed phases were obtained using the polyol method, resulting in selectivity towards higher alcohols, as high as 11.3% when supported on alumina. Segregation of cobalt and the formation of cobalt carbide were observed in the catalysts after catalytic testing, which may limit performance compared to the desired alloy phase.