Comparisons of the oxygen-handling properties of calcined CeO,, CeO2-AI2O3, RhO,-CeO,, Rh0,-CeO2/AI,O3 and La,O,-CeO, materials are made on the basis of their experimentally observed abilities to bring about R,-type homophase oxygen isotope equilibration of an equimolar (1602 + 1802) mixture at room temperature, and/or to induce low onsettemperatures (ca. 550 K) for pairwise heterophase oxygen isotope-exchange between gas-phase 1802 and oxygen-1 6 species from the oxide. Those oxygen equilibration/exchange processes were enhanced over precalcined Rho,-CeO, materials prepared from chloride-free precursors, but not over La,03-CeO,. That difference contrasted with expectations for similar concentrations of dopant-related, anion vacancy creation in each material, based upon XRD observations of the incorporation of each dopant into a slightly expanded CeO, (fluorite) lattice. Consideration is given not only to conventional contribution to oxygen equilibration/exchange by residual Rho, species at the Rho,-CeO, surfaces, but also to ways in which bulk-incorporated, variable-valency rhodium ions can indirectly facilitate those processes.