Pt-Sn was supported on titania and silica, and the resulting interactions. between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Mossbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO2 after calcinations, and Pt3Sn, PtSn and PtSn3 after reduction. Rietveld analysis shows that some Ti4+ are replaced by Sn4+ atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated. (c) 2007 Elsevier B.V. All rights reserved.