Long-afterglow phosphors Ca1.998-xMgSi2O7:Eu-0.002(3+), Ce-x(3+) (0 <= x <= 0.04) were prepared by a solid-state reaction tinder a weak reductive atmosphere. Spectroscopy measurements demonstrated that energy transferred from Ce3+ to Eu2+. The energy-transfer efficiency from Ce3+ to Eu2+ was 61%. Thermoluminescence measurement revealed that Ce3+ co-doped samples created much appropriate traps leading to the enhancement of the afterglow. The afterglow emission spectra revealed that Ce3+ in the co-doped samples acted as sensitizers and Eu2+ ill [CaO8] (535 am) acted as activators. The duration of co-doped samples was prolonged nearly two times compared with that of the Eu2+ single-doped sample. A possible afterglow mechanism was presented. and discussed. (C) 2009 The Electrochemical Society. [DOI: 10.1149/1.3176668] All rights reserved.