Sulphur dioxide is widely used in many industrial areas, for example in the production of sulphuric acid, and also as a reducing, bleaching, refrigerating agent and antioxidant. Due to a broad range of applications, it is one of the major atmospheric pollutants. Sulphur dioxide is a colourless gas with a strong odour. It is toxic, and its inhalation in high concentrations causes asphyxia, vomiting, and pulmonary oedema. This book presents research data from across the globe in the study of sulphur dioxide. Some topics in this compilation include a discussion of the receptor sites for sulphur dioxide; catalysts for the SO3 decomposition reaction; the physical properties of sulphur dioxide; the theoretical insights into the photoelectron spectroscopy of sulphur dioxide and sulphur dioxide emissions control.