Pr supported on gamma-Al2O3, TiO2 and ZrO2 are active catalysts for the CO2 reforming of methane to synthesis gas. The stability of the catalysts increased in the order Pt/gamma-Al2O3 < Pt/TiO2 < Pt/ZrO2. For all catalysts, the decrease in activity with time on stream is caused by carbon formation, which blocks the active metal sites for reaction. With Pt/TiO2 and Pt/ZrO2, deactivation started immediately after the start of the reaction, while the Pt/gamma-Al2O3 catalyst showed an induction period during which carbon was accumulated without affecting the catalytic activity.