Rare earth-doped TiO2 thin films have been successfully formed on glass and Si wafer substrates from aqueous solution through equilibrium reaction between metal-fluoro complex and metal oxide, in which Ln(3+)-ethylenediaminetetraacetic acid (EDTA) complex (Ln: rare earth metal) was added into the reaction solution. Ln/Ti ratio and crystalline structure of the film could be controlled by varying the initial concentration of Ln(3+)-EDTA complex solution. The obtained Ln-doped films were densely-packed and had no cracks. (C) 2004 Elsevier B.V. All rights reserved.