Several alumina-supported Ru catalysts prepared from different metal precursors were comparatively studied by H, and CO adsorption microcalorimetry and by Fourier transformed-infrared spectroscopy (FT-IR) of the chemisorbed CO molecule. The correlation of the results thus obtained from these techniques with those on the n-butane/H-2 reaction test, provides useful information about the type and distribution of the surface active sites on the supported metal crystallites. Also, the comparison of the results obtained from these complementary techniques with those reported for monocrystals or from other studies available in the scientific literature for Supported Ru catalysts, enables the tentative attribution of the type of exposed crystalline planes. In this way, the energetic distribution of surface sites has been shown to depend on the mean metal particle size as well as on the Ru precursor involved in the preparation. (c) 2005 Elsevier B.V. All rights reserved.