The sensitization effect in the IR-F spectroscopy by addition of SF6was investigated in case of acetone as a sample. We kept the partial pressure of acetone constant, varied that of SF6, and investigated the variations of the degree of sensitization. The experimental data shows that the degree of sensitization increases steeply and is saturated as the partial pressure of SF6becomes higher. The results were examined in terms of the kinetics of the intra-and intermolecular energy transfer involved in the emission of infrared radiation in question.