Pt-doped and SnO2-templated TiO2 can be prepared by sol-gel methods and are very active in CO oxidation especially at low p(CO) and high O-2:CO ratios. It may also have activity in CO oxidation promoted by water vapour at moderate temperatures of reaction. Scanning calorimetry and residual gas analysis suggest that O finds it relatively difficult to establish itself on a surface precovered with CO and it may be that water-generated OH groups at the Pt-oxide interface accelerate this particular process.