An oxidative formation of 1,4,2-oxathiazoles from readily available thiohydroximic acids is reported. A variety of alkyl, aryl, and heteroaryl substituents are well tolerated for both the thiohydroximic acid and activating fragments, and the reaction has been demonstrated on gram-scale. This reaction represents the only method currently available to prepare a diverse set of oxathiazoles and expands the chemistry of C-H oxidation via appended N-OH functional groups. Finally, we also demonstrate the rapid preparation of a 1,4,2-oxathiazole analog of an anticancer lead molecule.