Catalysts comprising between 1 and 3.6 wt% Au on TiO2 have been studied by Debye function analysis. The structure of the deposited particles in Au/TiO2, prepared by deposition-precipitation, in the presence of magnesium citrate, was predominantly fee cuboctahedral, with a size distribution between 3 and 4 nm. Optimized fits indicate a twin probability of similar to 9%. Au/TiO2 catalysts prepared by photodeposition were found to be much less active for CO oxidation than catalysts prepared by deposition-precipitation and comprised fee cuboctahedral particles between 1 and 7 nm in size.