The present paper delves into physical and chemical characterization of surface and bulk properties of the twelve 2 wt.% PtxIry catalysts employed in Part I for ring opening of naphthenic structures. The support materials (ceria, alumina, silica, silica-alumina, zirconia, H-SA and magnesia) were investigated using X-ray diffraction (XRD) for phase identification and adsorption/desorption of nitrogen to obtain the specific surface area and pore size distribution. The catalyst preparation via the incipient wetness technique was closely monitored and the final catalysts were examined by means of X-ray fluorescence (XRF), X-ray photoelectron spectroscopy (XPS) and quantitative TPR followed by dynamic pulse chemisorption of CO, Fourier transform infrared spectroscopy (Fr-IR) of adsorbed CO and NH3-DRIFTS. The XPS analyses are particularly comprehensive and involve all the catalysts in their fresh, reduced and spent states. The combined results from TPR, XPS and Fr-IR of adsorbed CO reveal that metallic Pt-Ir alloys are formed directly upon mild reduction. (c) 2005 Elsevier B.V. All rights reserved.