Sulphur dioxide (SO2) scrubbers may be used by electricity generating units to meet the requirements of Phase II of the Acid Rain SO2 Reduction Program. Additionally, the use of scrubbers can result in reduction of mercury and particulate matter emissions. It is timely, therefore, to review commercially available flue gas desulfurisation (FGD) technologies that have an established record of performance. The review of FGD technologies presented in this book describes these technologies, assesses their applications, and characterises their performance. Additionally, the book describes some of the advances that have occurred in FGD technologies. Finally, an analysis of the costs associated with applications of limestone forced oxidation, lime spray dryer, and magnesium-enhanced lime FGD processes is presented.