Tb3+ doped gadolinum oxybromide phosphors were synthesized by solid-state reaction. The GdOBr: Tb phosphor showed two intense emission bands, corresponding to D-5(3) --> F-7(5) and D-5(4) --> F-7(5) transition with the Tb3+ concentration. The luminescent properties of GdOBr: Tb phosphor were investigated by photoluminescence. To investigate the multipolar interaction scheme between Tb3+ ions, the decay behavior was analyzed using direct quenching. The energy interaction type of GdOBr: Tb phosphor was dipole-quadrupole interaction. In addition, the critical distance (R-c) value for energy transfer was calculated by the decay curve fitting parameter from the Inokuti-Hirayama equation. Cathodoluminescent emission spectra were compared with industrially manufactured green phosphors. (C) 2003 The Electrochemical Society.