Photocatalytic titanium oxide (TiO2) thin films are synthesized by the Nd:YAG pulsed laser deposition (PLD) technique. The influence of laser repetition rate and substrate temperature on the crystalline structure is investigated by X-ray diffraction (XRD) measurement. Films deposited at a substrate temperature of 150 degreesC exhibit the anatase form, regardless of the repetition frequency. In films deposited at 300 degreesC, however, when the repetition rate is increased the crystal form changes from rutile to anatase. The change in crystal form is probably caused by a drop in the surface temperature of the growing film. The effect is very sensitive to repetition rate, which changes the deposition rate. The results suggest that control of the laser-pulse repetition rate in PLD is a very important factor for obtaining highly efficient photocatalytic TiO2 thin films. (C) 2002 Elsevier Science B.V. All rights reserved.