TiO2 thin films were deposited on either glass or Si wafer substrate using a reactive magnetron sputtering by varying the process conditions including O-2/(Ar+O-2) ratio, working pressure, sputtering time and dc power, to examine the influence of surface morphology and crystallinity on photodecomposition efficiency of phenol and bactericidal activity of Escherichia coli (E. coli 078). The UV illuminated nanoporous anatase TiO2 films with a higher roughness (205 Angstrom) and crystallinity behaved as the best photocatalysts by 60% of phenol photodecom position and 70% of bacteria cell (E. coli) destruction. Therefore, it was conceivable that the photocatalytic efficiency may be governed by the specific surface area, which was directly related to the crystallinity and the roughness of the films. (C) 2004 Kluwer Academic Publishers.