It was found that the photocatalytic oxidative deoximation reaction is actually an autocatalytic process catalyzed by the generated ketone products. In contrast to reported deoximation methods, this reaction is metal-free and waste-free. The deoximation reaction is a significant transformation process in the industrial production of a variety of fine chemicals. The use of visible light as the driving force makes this method even more practical for the utilization of sustainable energy from an industrial viewpoint. Moreover, understanding the mechanism of the autocatalytic oxidative deoximation reaction may help chemical engineers to develop related techniques to avoid the decomposition of oximes, which are significant starting materials and intermediates during the production of fine chemicals and medicines.