Temperature-programmed isotopic exchange of O-18(2) with O-16 of several oxides was carried out in the 200-900 degrees C temperature range. The oxides can be ranked according to their maximal rates of exchange obtained at the following temperatures : CeO2, 410 degrees C >> CeO2-Al2O3, 480 degrees C approximate to MgO, 490 degrees C, ZrO2, 530 degrees C >> gamma-Al2O3, 620 degrees C >1 SiO2, 850 degrees C. Except on CeO2 and on CeO2-Al2O3 a simple exchange yielding initially (OO)-O-18-O-16 can be observed. With ceria containing oxides, the reaction occurs in part via a multiple exchange mechanism yielding initially O-16(2) which is indicative of the presence of binuclear species (O-2, O-2(-), or O-2(2-)) at the ceria surface. Chlorine-free rhodium catalysts supported on these oxides were prepared with metal dispersions between 32 and 89%. The presence of rhodium accelerates considerably the oxygen exchange with the support : the maximal rates of the exchange can be observed at much lower temperatures, by about 200-300 degrees C with respect to the bare oxides. This is attributed to a spillover of oxygen from the rhodium particles to the support. Isotopic exchange experiments carried out at temperatures (300-400 degrees C) at which the direct exchange is negligible allow for calculation of the coefficient of surface diffusion of oxygen on the oxides. At 400 degrees C, the relative mobility of oxygen (base 100 for gamma-Al2O3) is CeO2, 28 100 >> MgO, 500, ZrO2, 280 > CeO2-Al2O3, 180 > gamma-Al2O3, 100 >> SiO2, 1.7. Oxygen mobility can be paralleled with the surface concentration of basic sites measured by CO2 chemisorption (sites per nm(-2)) : CeO2, 3.23 > MgO, 1.77 > ZrO2, 1.45 > CeO2-Al2O3, 0.44 > gamma-Al2O3, 0.17 > SiO2, approximate to 0. Actually, the basicity of CeO2 cannot alone explain the exceptional mobility of oxygen on this oxide, due to a large part to the presence of oxygen vacancies. Above 400 degrees C, bulk oxygen diffusion can be observed on CeO2, ZrO2, gamma-Al2O3 and CeO2-Al2O3. Ceria possesses a very high internal mobility. The coefficient of bulk diffusion of oxygen in ZrO2 is about two orders of magnitude higher than in gamma-Al2O3, which contrasts with the relatively close values of their surface mobility. Except for CeO2, there is a good correlation between this surface mobility and the metal-oxygen bond strength in the oxide crystal.