The reaction of CO and ethylene on oxide-supported Rh particles was studied using temperature programmed desorption. The model systems investigated consisted of Rh particles on the following oxide supports: alpha -Al2O3(0001), yttria-stabilized zirconia (100) EYSZ(100)], CeO2 thin film on alpha -Al2O3(0001) and CeO2 thin film on YSZ(100). The results of this study demonstrate that both the ceria and YSZ supports are able to donate oxygen for reaction with carbon species adsorbed on the supported Rh particles. The reducibility of the ceria thin films was found to be influenced by the underlying oxide supports. Ceria films supported on YSZ(100) underwent reduction upon heating to 900 K, while those on alpha -Al2O3(0001) did not. (C) 2000 Elsevier Science B.V. All rights reserved.