The Tb3+ doped CaWO4 phosphors are synthesized via high temperature solid state reaction. The X-ray diffraction shows that small amount of Tb3+ does not have a significant influence on the structure of CaWO4. A broad absorption band of the WO42- group is observed from photoluminescence and the energy transfer from WO42- group to Tb3+ ions induces the f-f transition. The cross-relaxation between two adjacent Tb3+ ions weakens D-5(3)-F-7(j) transitions and enhances the D-5(4)-F-7(j) transitions, leading to a green long afterglow of the phosphors. The thermoluminescence curves centered around 75 degrees C reveal the trap depth for afterglow generation is about 0.74-0.77 eV. The optimum Tb3+ concentration for afterglow properties is about 1%.A deep hole trap is induced when Tb3+ concentration exceeds 1% and it suppresses the thermoluminescence and the decay properties. (C) 2011 Elsevier Ltd. All rights reserved.