Catalytic studies have shown that the activity of metal nanoparticles depends on their size and shape. Palladium nanoparticles with different morphologies have been prepared and embedded in a SiO2 and TiO2 matrix, and their catalytic performance in the solvent-free aerobic oxidation of 1-phenylethanol has been studied. The observed activity is strongly related to the exposed surface sites, being some of the active sites embedded in the matrix or blocked by residual organic species. (1 1 1)/(1 0 0) edge sites are involved in the oxidative dehydrogenation of 1-phenylethanol. The amount of these sites depends on particle morphology. Under our conditions, Pd-bars-SiO2 ( Pd nanobars embedded in SiO2) were found to be the most active. (C) 2011 Elsevier B.V. All rights reserved.