The subject of this book, The Exergy Method also known as the Availability Analysis, is a method of thermodynamic analysis in which the basis of evaluation of thermodynamic losses follows from both the First and the Second Law of Thermodynamics rather than just the First Law. This book is particularly intended for engineers and students specializing in thermal and chemical plant design or operation as well as applied scientists concerned with various aspects of conservation of energy. It introduces the subject in a manner which can be understood by anyone who is familiar with the fundamentals of Applied Thermodynamics. Numerous examples are used in the book to aid the reader in assimilating the basic concepts and in mastering the techniques. Dr Tadeusz J. Kotas joined the Department of Mechanical Engineering of Queen Mary College as a member of teaching staff in 1957. His main areas of interest were Mechanics of Fluids and Applied Thermodynamics, obtaining a PhD degree for his work in the former subject. His work in the latter subject focused on the Exergy Method, contributing to its development through his research and publications and to its dissemination through courses which he ran in Britain and in a number of European countries for practicing engineers and academics.