The catalytic production of hydrogen through the carbon dioxide reforming of methane was carried out both in a plug-flow reactor and in a dense Pd/Ag membrane reactor. In the former device, the activity and stability of Pt/La2O3 were investigated and compared to the Rh/La2O3 solids. None of the catalysts assayed showed carbon deposition through TGA although the Raman spectra always included weak bands assigned to graphitic carbon. The best Pt and Rh catalysts were used in the membrane reactor and in both cases significant increases in CH4 and CO2 conversions were recorded. Despite their similar activities, the Rh (0.2%)/La2O3 was much more stable than the Pt/La2O3 formulations. The origin of the deactivation was found to be the partial sintering of the platinum after 100 h on stream at 823 K. Rh interacted more strongly with the support and this impaired the sintering of the well-dispersed metal. (C) 2002 Elsevier Science B.V. All rights reserved.