Book excerpt: Isotopic Assessment of Heterogeneous Catalysis deals with the use of isotopic tracing to study the reaction mechanisms involved in heterogeneous catalysis. It presents special methods for using isotopic and radioactive atomic species for obtaining meaningful kinetic data that can be quantitatively used in mechanistic modeling. It also considers a number of industrial reactions under steady-state reaction conditions in which superposed tracer transfer is also at steady state. This book is comprised of eight chapters and begins with an introduction to heterogeneous catalysis and an approach to reaction modeling, as well as the experimental reactors for obtaining the type of measurements and data needed in transient modeling. The application of isotopes in studies of heterogeneous catalysis is also discussed. Subsequent chapters focus on the choice of intermediates and reaction steps in tracer experiments; the number of overall stoichiometric chemical reactions that can occur in order to generate product molecules from reactants; superposition modeling of mechanisms; and steady-state tracing. Transient tracing and the development of rate equations are also described. This monograph is intended primarily for students and teachers of such subjects as physical chemistry, as well as research scientists and technologists.