Gold nanoparticles were first supported on protonic titanate nanotubes with the formation of Au/titanate nanocomposites. They were further transformed to Au/titania nanocomposites via an acetic acid treatment at 70 degrees C for 60 h. The porosity, crystal structure and morphology of those composites have been studied by X-ray diffraction (XRD), High-resolution transmission electron microscope (HRTEM), and low-temperature nitrogen adsorption. Catalytic tests for CO oxidation show that the Au/titanate nanocomposites had a promising activity with complete conversion of CO at 70 degrees C and that of Au/titania was at room temperature (25 degrees C). Both catalysts exhibited good thermal and long-term stabilities. The influence of the crystal vacancies and surface properties of the titanate and titania supports on the catalytic activities were evaluated. (c) 2007 Elsevier B.V. All rights reserved.