Tetrakis(dimethylamido) titanium (TDMAT) was evaluated as a possible precursor for TiO2 ALD for the first time using H2O as a counter-reactant. Film growth rate, surface morphology, crystallinity, and film composition on the deposition temperature were studied at substrate temperatures of 90-210 degrees C. Except with the ALD regime, 120-150 degrees C, the film growth rate decreased linearly with growth temperature below 120 degrees C and above 150 degrees C. All films prepared in this study were in the amorphous and the films were highly pure. After annealing the as-deposited films at temperatures of 300-800 degrees C, change of crystallinity and photocatalytic effectiveness of the TiO2 were investigated. The crystal structure of the films was changed to anatase at annealing temperature above 300 degrees C and rutile phase was observed with a sample annealed at 500 degrees C. After annealing at 800 degrees C, only rutile phase of TiO2 was observed. The crystalline films annealed were shown to have photocatalytic activity in decomposing methylene blue in aqueous solution. (c) 2005 Published by Elsevier B.V.