The role of the adsorbed reactants and intermediates on the performance and deactivation behavior of Mg-Zr mixed oxides as acetone self-condensation catalysts is studied in this work. DRIFT spectroscopy was used for identifying the adsorbed species and following their evolution during both acetone self-condensation reaction and thermo-desorption of pre-adsorbed reactants and products. The evolution of these species and the results of the characterization (nitrogen physisorption, temperature-programmed oxidation, and catalyst leaching) of catalysts samples taken in a continuous reactor at different temperatures (523, 623, and 723 K) and times on stream allow to determine that two concomitant deactivation causes are present in this reaction: the strong adsorption of dimers and trimers on the catalyst surface (especially important at the lowest temperature) and the formation of heavy condensation products physically deposited on the catalyst surface (more relevant at the highest temperature). (C) 2015 Elsevier Inc. All rights reserved.