SrAl2O4 phosphors co-doped with Eu2+, Dy3+, and Nd3+ ions are synthesized through a citric acid assisted sol-gel combustion process. The crystalline phases and crystallinity of the synthesized phosphors are studied by X-ray diffraction analysis. Strong persistent phosphorescence at 882 nm is observed as a consequence of irradiation by ultraviolet light at 370 nm due to the persistent energy transfer from excited Eu2+ ions to Nd3+ ions. The optimum doping concentration of Nd3+ ions is estimated to be similar to 2%, when the concentration of Eu2+ and Dy3+ ions are 1 and 1.5%, respectively, considering the energy transfer efficiency and the near infrared phosphorescence intensity. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3518767] All rights reserved.