The aim of this study is to examine the photocatalytic activity of TiO2 (P25)-ZnO nanocomposite. The precursors of the TiO2-ZnO nanocomposite were deposited on a low cost ceramic substrate using the simple roll-coating method. We seek to improve the photocatalytic performance and the mechanical adherence of the TiO2 nanoparticles by adding ZnO. The photocatalytic properties of the nanocomposite were tested through the bleaching of polluted water. These properties were optimized by varying the composition of the nanocomposite precursors, deposition conditions and temperature annealing. A systematic study of the nanocomposites was made using ultraviolet-visible spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). These characterizations allowed us to establish a relationship between the photocatalytic performances and the ZnO ratio using an azo-dye (methyl orange). It was found that the kinetic degradation increases with the increasing of the ZnO ratio. The Photodegradation of the dye using the sole ZnO was found to be more efficient than the P25 TiO2 and the TiO2-ZnO nanocomposite itself. The discussions were based on the mobility and lifetime of the charge carriers generated in the ZnO or in TiO2-ZnO nanocomposite.