Theoretical developments in the surface physics and chemistry of transition metal compounds can be of paramount importance in catalysis, electronic devices, corrosion etc. In this book, a unified survey of the most important methods in theoretical chemistry applied to reactions and processes that occur on transition metal surfaces is presented together with a discussion of their advantages and limitations. Theoretical modelling of chemisorption, diffusion, desorption, effect of promoters, formation of adsorbed intermediates, surface reconstruction, segregation of impurities etc. are reviewed. This book aims to serve as a source of reference material for researchers as well as a text for graduate students following courses on theoretical and computational chemistry related to catalysis and surface chemistry and physics.