The popularity of semiconductor-based photocatalysts is still increasing, due to their expanding fields of application. During my doctoral work, I prepared ZnO photocatalysts with various morphology and examined how the structural and morphological modifications affect the photocatalytic performance. At first, I demonstrated that a structural feature, the preferential orientation of crystallites along (002) crystallographic planes of the ZnO crystallites correlates with the photocatalytic activity using a reduced experimental design (Box-Behnken) for the solvothermal synthesis of ZnO. Morphological modification of semiconductors is also an important aspect in the field of heterogeneous photocatalysis, as can directly influence the activity. I modified the previously mentioned synthesis method to prepare ZnO spheres, using diethanolamine as the morphological agent. By applying two different ZnO precursors, respective to their mixtures I showed that the average size of ZnO spheres can be tuned between 155 nm and 3 μm. In addition, I demonstrated that the previously described structural feature can still be controlled, without modifying the morphology. I showed that spherical morphology and photocatalytic performance can be tuned separately. Lastly, I further modified the synthesis method using carbon sphere templates to prepare ZnO hollow spherical morphology. Despite the application of the templates, the preferential orientation of crystallites is still possible and the photocatalytic performance of the hollow spherical ZnOs was superior compared to the reference solid spherical ZnOs. I further improved the catalytic activity of ZnO hollow spheres by doping with noble metal (Au, Pt) nanoparticles. Overall, the achieved results demonstrate that the preferential orientation of crystallites along (002) is a determining aspect of the photocatalytic activity, regardless of the morphological modifications applied.