Book excerpt: Numerous solvents used in chemical processes have poisonous and unsafe properties that pose significant ecological concerns ranging from atmospheric emissions to the contamination of water effluents. To combat these ecological threats, over the course of the past two decades, the field of green chemistry has grown to develop more natural reaction processes and techniques involving the use of nonconventional solvents to diminish waste solvent production and thus decrease negative impact on the environment. Ionic liquids in particular are more environmentally friendly substitutes to conventional solvents, and as such, have seen more widespread use in the past decade. They have been used in such processes as extraction, separation, purification of organic, inorganic, and bioinorganic compounds, reaction media in biochemical and chemical catalysis, green organic and drug synthesis, among other industrial applications. Thus, in proving themselves a suitable greener media for economic viability in chemical processes, ionic liquids are leading to more sustainable development. This edition explores the application of ionic liquids as a green solvent. It contains a state-of-the-art overview on ionic liquids as green solvents for chemical processes and techniques, as well as some of their useful industrial applications.