Microcalorimetric measurements of the adsorption of CO on a Rh/0.9Te/SiO2 catalyst were performed at 203, 253, and 303 K. The initial heats of CO adsorption were approximately 87 kJ/mol, and this value is much weaker than the value of 160 kJ/mol measured on a Rh/SiO2 catalyst. Infrared spectra were collected for CO adsorbed on Rh/SiO2, Rh/0.7Te/SiO2, and Rh/0.9Te/SiO2 catalysts. The primary IR bands were located at frequencies near 2030 cm(-1) for the Rh/Te/SiO2 catalysts, compared to the higher frequency of 2080 cm(-1) for CO on Rh/SiO2. In addition, the intensity of the IR band for CO on the Rh/Te/SiO2 catalysts increased irreversibly when the samples were warmed from 203 to 303 K. Periodic self-consistent DFT-GGA calculations were carried out to study the adsorption of CO on slabs of Rh(111), RhTe(0001), and RhTe(1120). These calculations show that CO adsorbs strongly on Rh(111), Rh-terminated RhTe(0001), and RhTe(1120) surfaces, with heats higher than 160 kJ/mol. In contrast, weaker adsorption was calculated for adsorption of CO on Te-terminated RhTe(0001) surfaces, with a heat near 70 kJ/mol. Thus, the Te-terminated RhTe(0001) surface appears to be the best model surface for Rh/0.9Te/SiO2 catalyst, based on the combined results of microcalorimetric measurements and DFT calculations. Adsorption of CO on the hcp site of the Te-terminated RhTe(0001) surface leads to a reconstruction in which the Rh atom bonded to CO is pulled from its position in the second layer to a location above the surface. A lower limit for the activation energy barrier of this CO-induced surface reconstruction is 44 kJ/mol (which corresponds to the barrier of the more exothermic O-induced surface reconstruction). This CO-induced surface reconstruction may be the origin for the experimentally observed increase in the intensity of the IR band for adsorbed CO when Rh/Te/SiO2 samples are warmed from 203 to 303 K in the presence of CO. (C) 2003 Elsevier Science (USA). All rights reserved.