Since photocatalysts in the form of nanoparticulated powders represent problematic form for practical application due to nanoparticles possible release to the environment, it is necessary to focus on transfer and deposition of photoactive nanoparticles/nanocrystallites as well-fixed thin films or stable porous monoliths/aerogels. These efforts are accompanied hand by hand with the development of treatment techniques resulting in direct crystallization of nanoparticles on various types of substrates, or in monolithic/aerogel form. In this research field calcination may be surpassed by high-pressure techniques using supercritical carbon dioxide, subcritical water or pressurized hot solvents, since pressure is a factor significantly affecting the whole chemicals dissolution and crystallization process, thus, final photocatalyst design. This talk covers important fundamental aspects in nanoparticulated TiO2-based powders designed by using supercritical and pressurized hot water and solvents, and subsequent transfer of obtained knowledge to design of nanocrystalline thin films and monoliths/aerogels.