PURPOSE: To obtain oxophorone, in high efficiency and selectivity, by oxidizing α-isophorone with oxygen in the presence of phosphomolybdic acid or silicomolybdic acid and copresence of an alkali metal compound or an aromatic amine.

CONSTITUTION: The objective compound of formula II useful as an intermediate for vitamin E, tobacco flavor or carotinoid such as rhodoxanthin, etc. economically from an easily available raw material, by oxidizing α-isophorone of formula I with oxygen at room temperature W130°C, preferably at 70W110°C, preferably in the absence of solvent, in the presence of phosphomolybdic acid or silicomolybdic acid, a nd in the copresence of an alkali metal salt such as bicarbonate, carbonate, acetate, oxide or hydroxide of Li, Na, K, Cs or Rb, or an aromatic amine such as pyrazine, triazine, 4,4'-dipyridyl, triphenylamine, etc.