Optical properties of sexithiophene films grown on TiO2(110) surfaces have been investigated by photoluminescence characterization i) at different growth stages, namely for ultra thin wetting layer films and for thicker films, and ii) as a function of the substrate surface order. The photoluminescence spectra of the wetting layer grown on the ordered TiO2(110) surface suggest that the layer is formed by isolated and/or weakly mutually interacting molecules. While the electronic, geometric, and morphologic properties of the thicker sexithiophene films dramatically depend on the presence or the lack of the TiO2(110) surface order, their optical properties show almost no dependence on the substrate surface order. (c) 2008 Elsevier B.V. All rights reserved.