Originally published in 1967, this book gives a resumé of the state of knowledge on selected topics of importance at the time concerned with the mechanisms of chemical reactions induced by heat or light, and of the rates at which they proceed. The reactions discussed range from very simple atomic reactions to the more complex chain reactions involved in such well-known processes as combustion, flame and the production of polymers used in the plastics industry. During the forty-five years preceding publication, reaction kinetics became one of the major divisions of physical chemistry. Our knowledge of the mechanisms of the chain reactions involved in photochemistry, combustion and polymerization, and our understanding of chemiluminescence and the flow of energy between molecules and between different modes within molecules, grew enormously.