SrAl2O4 phosphors doped with Eu and Dy are known to exhibit a bright and long-lasting afterglow (AG) after irradiation with fluorescent light or sunlight. It has been proposed that Dy played the role of a hole trap and Eu acted as an electron trap. However, an open question of the hole trap and its trap depth has been remained. The measurement of afterglow was carried out on the SrAl2O4 samples doped with Eu and rare earth ions (Ln = Y, lanthanides! in order to systematically investigate the role of the codopants for long- lasting afterglow mechanism after ultraviolet irradiation. All samples exhibited a broad AG emission due to the electronic transition from 4f(6)5d to 4f(7) of Eu2+. In addition, the Pr, Nd, Ho, or Er-codoped samples also had the emissions due to the f-f electronic transition that are originated in the two-photon excitation reaction. Furthermore, the order of observed AG lifetime was different from the order of tendency that trivalent ion becomes divalent or tetravalent ion. So hole trap is assumed to be Sr2+ vacancy rather than Ln(3+). (C) 2004 The Electrochemical Society.