The influence of the sulfur impurity on the CH4-CO2 reforming reaction over Rh catalyst was studied. The activity of Rh/Al2O3 varied remarkably depending on the kinds of Al2O3 Support. Based on the EXAFS and TPR measurements, the variations were ascribed to the changes in the reducibility of Rh as a result of the interaction with SO42-present as impurity in the alumina support. In agreement with the assumption, the activity of Rh improved significantly as SO42- was removed from the Al2O3 support. Based on the EXAFS analysis, the role of SO42- anion was ascribed to the inhibition of the reduction of RhCl3 to give metal Rh. (C) 2006 Elsevier B.V. All rights reserved.