Highly dispersed Pt nanoparticles on modified mesoporous Al-SBA-15 were obtained by a solid state impregnation (SSI) methodology, which consisted of a physical mixture of Al-SBA-15 support with a given amount of Pt(acac)(2) in order to have 1 wt.% of Pt on the final solid. The solid mixture was ground vigorously and annealed at 180 degrees C (e.g. the sublimation point of Pt(acac)(2)) for 0.5 h and then at 400 degrees C in inert atmosphere, to decompose the organic ligand. The materials were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) by applying high angle annular dark field (HAADF) technique, nitrogen physisorption, pyridine adsorption by infrared spectroscopy (FTIR), X-ray photoelectronic spectroscopy (XPS) and FUR of CO adsorption. Catalytic activity of Pt nanoparticles was evaluated in naphthalene hydrogenation (HYD) as test reaction. The results were compared with those obtained on Pt nanoparticles dispersed on Al-SBA-15 by wet impregnation (WI) method. Both SSI and WI methods produce significant differences in the population of flat and edge sites on the Pt nanoparticles with dimensions around 1.0 nm. However, Pt nanoparticles obtained by SSI showed higher activity upon naphthalene HYD than those obtained by WI method, which was explained by the higher density of edge sites measured by FTIR of CO adsorption. (C) 2011 Elsevier B.V. All rights reserved.