A catalyst system consisting of core-shell nanostructures with Au core and porous TiO2 shell was synthesized and characterized for room temperature CO oxidation. The core-shell structures were prepared by colloidal methods starting from pre-formed 3 nm Au particles in solution and then adsorbed on to high-surface area, functionalized hydrophobic Al2O3 support. The obtained Au@TiO2/Si-Al2O3 catalyst showed higher activity and thermal stability when compared to a conventional Au/TiO2 sample prepared by impregnation of the same Au particles on to commercial titania P25. The core-shell catalyst was able to maintain its activity and 3 nm Au particles size upon calcination up to 600 A degrees C, whereas the Au/TiO2 sample was found to sinter. Furthermore, it was found that the crystallization of TiO2 was suppressed in the core-shell structure, resulting in a thin layer of small TiO2 particles, which is favorable for the dispersion and thermal stability of Au nanoparticles. .