CO2 reforming of methane has been studied over Pt/Al2O3 model catalysts in a temperature range of 600-800 degrees C using steady-state and transient methods (Transient Response Method (TRM) and DRIFT-MS). Pt-supported catalysts were prepared using two different alumina (gamma-Al2O3(S) Sasol-Puralox and a synthesized gamma-Al2O3(N) with nanofibrous structure). Catalysts and supports were characterized by conventional methods (XRD, TEM, A(BET), XPS) before and after reaction. Pt-0 species are present in the catalysts, with a higher relative contribution for the catalyst that has a nanostructured support. Pt/gamma-Al2O3(N) catalyst presented the best performance in reactivity and showed a low rate of carbon formation and a minimal water production. From TRM and DRIFT-MS results it can be concluded that, when CO2 and CH4 are fed separately into the reaction system, they are activated over the catalytic surface. Besides, when both reactants are fed contemporaneously the presence of CHx species promotes the CO2 activation that is responsible for the reforming reaction. (C) 2009 Published by Elsevier B.V.