High pressures play a more and more important role in modern technology. Examples are the supercritical fluid extraction of medical drugs and dyes from biological material, the handling of compressed or liquefied gases (including natural gas or hydrogen), the operation of modern thermal power plants, and various technical processes for controlled particle formation. High-Pressure Fluid Phase Equilibria, Second Edition enables understanding of the complicated phase behavior that fluid or fluid mixtures (liquids, gases, or supercritical phases) can exhibit at elevated pressures. The underlying thermodynamic equations are explained, and robust algorithms for the computation of such equilibria (including solid–fluid equilibria) are proposed. Since the publication of the first edition of this book, there have been many new developments, for instance, differential equation methods for the computation of phase equilibria, accurate numerical differentiation, and high-precision equations of state (e.g., the GERG model). Moreover, more detail and explanation has been added on important topics that were only briefly examined in the original book to better assist the reader, such as expansion processes and chemical reactions). The book remains invaluable as a single resource for grasping the intricacies of fluid phase behavior. It enables the readers to write or improve their own computer programs for the calculation of phase equilibria. It will appeal to graduate students of chemical engineering and university research staff involved in chemical engineering of supercritical fluids or the physical chemistry of fluids; the book can also serve as the basis of lectures or advanced students’ seminars.