Restructuration of AuPd/CeO2 catalysts is observed during 1,5-cyclooctadiene hydrogenation, with gold surface segregation in which gold acts as a diluent of Pd surface sites. The composition of the catalyst influences the catalytic behavior, and an optimum is observed at a Pd/Au molar ratio of 0.13, as determined by X-EDS STEM. Pd-Au/CeO2 shows higher hydrogenation rates (11.2 x 10-5 mol/g s) versus the unpromoted Pd/CeO2 catalysts (1.7 x 10-5 mol/g s), and the Pd/TiO2 (7.5 x 10-5 mol/g s) catalysts used as conventional hydrogenation catalysts. Since the active sites are generated under reaction conditions, characterization of the catalysts after quenching the reaction at specific reaction times was required. (C) 2015 Elsevier B.V. All rights reserved.