Oxidation reactions are an important chemical transformation in both academia and industry. Among the major advances in the field has been the development of catalytic processes, which are not only selective and efficient, but also allow the replacement of common stoichiometric oxidants with molecular oxygen, ideally from air at atmospheric pressure. This results in processes with higher atom efficiency, where water is the only side product in line with the principles of green chemistry. Focusing on the use of molecular oxygen as the terminal oxidant, this book covers recent advances in both heterogeneous and homogeneous systems, with and without metals and on the “taming” of the highly reactive oxygen gas by use of micro-flow reactors and membranes. A useful reference for industrial and academic chemists working on oxidation processes, as well as green chemists.