This book is dedicated to studying the thermodynamic bases of the structure-function relationship of proteins. It moves from the elementary principles of physical chemistry to the most current topics of biochemistry, including those that may be subject to some controversy. It considers thermodynamic properties related to the stability and function of proteins from the point of view of physics in a language that, without sacrificing conceptual rigor, is easy to read. Detailing the thermodynamics of protein-ligand interactions, protein naturation, allostery, oxidative phosphorylation and protein phosphorylation, the book will be of interest to students and teachers of chemistry, physics, biochemistry and biotechnology.