Advanced oxidation processes (AOPs), which involve the in-situ generation of highly potent chemical oxidants such as the hydroxyl radical, have emerged as an important class of technologies to accelerate the non-selective oxidation and thus the destruction of a wide range of recalcitrant organic contaminants in wastewater which can not be eliminated biologically. Under proper conditions, the components to be removed are converted completely to C0₂, water and mineral salts. This review discusses the various possible processes and the state-of-the-art with respect to practical applications and their potential in particular in the treatment of industrial wastewaters.