Covering all major aspects of photocatalysis, including the latest findings and insights on catalyst design, kinetic studies, and reactor engineering, this is a semi-empirical how-to guide, based on the authors' extensive experience and a thorough scan of the existing literature. Each chapter contains relevant examples and exercises, making the material suitable for university courses, while this knowledge is polished up to the engineering stage allowing its application in real reactors and purification units, with commercially produced reactors also considered.