On oxidation with aluminium tert.-butoxide, aconitine yields a product, aconitinone. The latter on heating produces a methoxyl-free compound, designated as aconitoline, which has been shown to be an all-unsaturated ketone from its U. V. and I. R. spectra. An infra-red absorption spectrum of pyroaconitine reveals that pyrolysis of aconitine proceeds through the formation of an ethylenic linkage and not an epoxy group. Pyrolytic products obtained at a higher temperature are also described.