Nanocrystalline thin films of important surface roughness and complexity were prepared by screen-printing of commercial TiO2 powder. The screen-printed titania films were tested in the photocatalytic decomposition reaction of methyl orange under UV light (350 nm). The photocatalytic activity strongly depends on the titania paste components and especially on the presence of a surface modifier (acetyl acetone) combined with a rheology controlling agent (ethyl cellulose). This results in improvement of the paste viscosity and optimization of the films morphology. Experiments under direct full sunlight illumination prove the importance of the screen-printed films for practical applications. (C) 2007 Elsevier B.V. All rights reserved.