The observation of energy transfer between the Al3+ and thr Pr3+ in SrTiO3 is discussed. For the purpose of calculating the critical distance (R-c), we considered transfer from a narrow band emission of the Al3+ ion to a broad band excitation of the Pr3+ ion. In order to ascertain the calculated critical distance based on spectral overlap data, we compared our results, to those from the concentration quenching data. The cathodoluminescent measurement was carried cut (operational pressure 10(-6) Torr) by using an electron-beam excitation at 100 mu A/cm(2) within an 800 V range. The emission spectra and the spectral coordinates were compared with industrially manufactured red phosphors.