Ceria-supported platinum and cobalt-based catalysts were investigated for the hydrogenation of CO at atmospheric pressure and 220 degrees C by operando diffuse reflectance FT-IR spectroscopy. The surface of Pt/Co/CeO2 samples was constituted of alloyed phases following reduction at 450 degrees C. Cobalt-rich domains were then gradually formed under a CO/H-2 feed at 220 degrees C and atmospheric pressure. Pt-rich and Co-rich domains could be differentiated by the difference in reactivity of CO(ads) on the corresponding sites following CO removal from the feed. Pt is probably catalytically inactive under reaction condition, being poisoned by CO. Our data are consistent with Pt facilitating the dispersion and/or reduction of cobalt, although this could not be measured directly. The surface of ceria was initially covered with formates species that were gradually replaced with acetates, stressing the ability of ceria-promoted samples for improved oxygenate selectivity reported elsewhere. (C) 2016 Elsevier B.V. All rights reserved.