The electro-oxidation of three isomeric methyl benzoxazines has been studied in acetonitrile and methanol in either neutral or alkaline media. Oxidation potentials have been determined and the reactivity of the benzoxazine cation radicals estimated. In alkaline methanol, the mechanism changes in favour of oxidation of the benzoxazine anion, and formation of a thin polymer layer is observed on metallic substrates. The resulting polymers were analysed by X-ray photoelectron spectroscopy measurements and a polymer formula has been proposed.