The reforming of CH4 with CO2 (dry reforming) has been studied on a series of Al2O3-supported Rh-Cu catalysts. The reaction has been found to proceed on these systems through a bifunctional mechanism, in which the activation on methane takes place on the rhodium phase while carbon dioxide is activated on the support surface via formate intermediates. The addition of a metal, such as copper, inactive for methane activation, has allowed us to evaluate the role of the interfacial Rh-Al2O3 sites in the reaction. The presence of copper reduces the stability of the catalysts, though it does not have any effect on the initial activity per surface exposed site. It indicates that the dry reforming of methane is not a structure-sensitive reaction and that catalytic activity, largely affected by the alumina support, is dependent on the number of surface exposed rhodium centers. (C) 2000 Academic Press.