Effects of internal stress on photocatalytic properties have been investigated on titanium dioxide films deposited by reactive magnetron sputtering. Atomic peening effects by bombardments of high-energy particles in sputtering processes should generate not only compressive stress, but also oxygen defects in the films. Therefore, the films with higher compressive stress performed almost no photocatalytic activity. Furthermore, compressive or tensile stress was applied on the films deposited on curved micro sheet glasses by flattening the substrates after the deposition by external force. It was found that the photodecomposition activity of the films applied the slight compressive stress improved clearly, whereas the one of the films applied the tensile stress degraded. (C) 2007 Elsevier B.V. All rights reserved.