Thin nanocoatings prepared by chemical deposition of 6.0-nm titanium oxide oxo-particles on glass supports show an increased photocatalytic activity, which can be as high as that of the best commercial crystalline powders and even higher. In the present Letter, we report on original method of nanocoatings preparation and on effect of the coating mass on its photocatalytic activity. We show that internal efficiency of this photocatalyst increases with a decrease of its mass. Moreover, the very first layer of oxo-particles possesses both high mechanically stability and the maximum efficiency. No photocatalyst deactivation has been observed. (c) 2006 Published by Elsevier B.V.