Photocatalytic processes. Absorption of radiation and its subsequent physical and chemical changes. The course of photochemical reactions. Photocatalytic reactions on semiconductor catalysts. Semiconductor photocatalysts. Sources of radiation. Laboratory photochemical reactors. Mechanism and kinetics of photocatalytic reactions. Homogeneous and heterogeneous photocatalysis. Influence of the wavelength, temperature, pressure and reductants on the photocatalytic reaction. Influence of surface modification and doping of the catalyst surface. Immobilized catalysts. Methods of application and methods of characterization of thin films. The application of photocatalytic processes in environmental protection.