The interaction of ethanol and its evolution to n-butanol over different MgAl mixed oxides derived from hydrotalcite precursors is studied by FTIR and in situ DRIFT-MS experiments. The evolution of different surface species is monitored as a function of thermal treatments. Acetaldehyde appears as a primary intermediate which converts over the mixed oxides to C4 products through the aldol condensation reaction. However, acetaldehyde also produces surface carboxylate species which compete for the active sites and make the condensation process less efficient. (C) 2013 Elsevier B. V. All rights reserved.