Publisher Summary The knowledge of catalytic mechanisms is limited because the majority of useful catalysts for practical reasons are heterogeneous and thus, unsuitable for mechanistic studies. The book, “Advances in catalysis and related subjects, volume 23,” deals with hydrocarbons on metals—the important role in the academic studies of deuterium exchange reactions. Using this method, Anderson takes ultrathin metal films with their separated crystallites as idealized models for supported metal catalysts. Sinfelt is concerned with hydrogenolysis on supported metals and relates the activity to the percentage d character of the metallic bond. Th. Wolkenstein's article provides mechanisms for certain light-accelerated catalytic reactions on solids. This is a field where very explicit models may be constructed in relation to the band theory of semiconductors and where detailed mathematical treatments have been made and compared with experiment. In addition, enzyme models are discussed in the book.