Triplet states of O-acyloximes were studied for the first time by means of laser absorption spectroscopy. Energy transfer experiments showed that the acyl moiety has no effect on the triplet energy, which depends only on the ketone oxime part. It was observed that the difference between the tripler energy of the parent ketone and that of the oxime varies, depending on the oxime structure. This behaviour is explained on the basis of a non-vertical character of the energy transfer reaction.