This publication arises from continued international efforts to develop radiation technologies for water and wastewater treatment. Radiation processing is an additive-free process that uses the short lived reactive species formed during radiolysis of the water for efficient decomposition of pollutants therein. The application of gamma rays or electron beams shows promise in the development of cost effective and efficient new technologies. This publication summarizes a number of studies conducted within the framework of an IAEA coordinated research project aiming at advancing and disseminating knowledge in this promising field.