An investigation has been made of the vapour-phase reaction of isophorone (3,5,5-trimethyl-2-cyclohexen-1-one) with ammonia and hydrogen at a temperature of 160-230 degrees C on an oxide copper-zinc-aluminium catalyst SNM-1 and a reduced, promoted, sintered iron catalyst. The composition of the main reaction products has been established, and schemes of their formation are proposed.