This is a comprehensive piece of work providing the reader a powerful resource for the design, development and performance evaluation of photocatalytic reactors. This book will be used as a reference for a graduate course in photocatalysis. It will also be valuable to undergraduate students, graduate students, researchers, environmental consultants or advisors, environmental auditors, engineers, technicians, scientists, governmental agencies, and environmental agencies or institutions interested in photocatalysis. This book will be a guide to the understanding of the principles and of the applications of photocatalysis technology. The book is also organized in such a manner that there is always good integration of basic principles, literature review, and applications. The main focus of this book is on the chemical reaction engineering aspects of the heterogeneous photocatalysis. Special attention is addressed to kinetic modeling, reactor irradiation, and reactor design of photochemical reactors. The book also reports an interesting review of practical applications of pollutant conversion in water and air.