Photosensitized oxygenation products of a series of methoxybenzenes in methanol were isolated and their structures elucidated. 1,2,4,5-Tetramethoxybenzene (I) gave 2,5-dimethoxy-p-benzoquinone (II) and an enone (III). 1,2,3,5-Tetramethoxybenzene (IXa) and pentamethoxybenzene (XXII) yielded diketones Xa and XXIII, respectively, Hexamethoxybenzene (XIV) gave a triketone hydrate (XVII). Mechanisms involving