This book provides a complete guide on tools and techniques for modeling of supercritical fluid extraction (SFE) as well as sub critical fluid extraction (SCFE) processes and phenomena. It provides details for both SFE and SCFE from managing the experiments to modeling and optimization. It includes the fundamentals of SFE as well as the necessary experimental techniques to validate the models. The optimization section includes the use of process simulators, conventional optimization techniques and state-of-the-art genetic algorithm methods. Numerous practical examples and case studies on the application of the modeling and optimization techniques on the SFE processes are also provided. Detailed thermo dynamical modeling with and without co-solvent and non equilibrium system modeling is another feature of the book. The book consists of seven chapters. Chapter one provides an overview of the field of SFE/SCFE and their importance and relation to food, cosmetic and pharmaceutical industries. Chapter two covers SFE/SCFE fundamentals and presents process descriptions. Chapter 3 discusses thermodynamic modeling of SFE including thermodynamic modeling in the presence of co solvent and also non-equilibrium state modeling. Chapter 4 provides details on the general modeling as well as optimization tools. Chapter 5 covers the general modeling techniques illustrated in chapter 4 and applies it for supercritical and sub critical modeling. Chapter 6 applies the optimization tools (traditional/genetic algorithm) for supercritical subcritical modeling. Finally, chapter 7 describes the procedure on how to design and mange experiments in SFE.