Judging from the properties of some its derivatives, peimine (I) was found to be a saturated tertiary base having two secondary and one tertiary hydroxyl groups. Oxidation of (I) with chromium trioxide gave a diketone, peiminone (V), and an oxidation of the product (V) with selenium dioxide afforded dehydropeiminone. Dehydropeiminone was assumed to have a 1-en-3-one structure from the ultraviolet spectrum of its perchlorate (VII).