This is an in-depth monograph covering the topic of energy transfer and reactions on solid surfaces. This topic is of great interest now because of its applications to catalysis and solid-state electronics, including the manufacture of semiconductors, integrated circuits and other solid state devices. Initially it describes what is meant by heterogenous reaction dynamics. Basically, this is the study, on a molecular level, of the elementary dynamics of energy transfer and reactions at surface. The emphasis of the book will be on well characterized solid surfaces. Energy transfer and reactions are broadly defined to include phase transitions in adsorbed layers, diffusion, the absorption process itself, and energy transfer between adsorbate and subtrate, as well as gas-surface energy transfer, catalytic and oxidative type surface reactions.