Green phosphors K2BaW2O8:Tb3+(1.0 mol%) were synthesized by solid state reaction method. Differential thermal analysis was applied to trace the reaction processes. Three endothermic values of 95, 706, and 1055oC correspond to the loss of absorbed water, the release of carbon dioxide, and the beginning of the melting point, respectively. The phase purity of the powders was examined using powder X-ray diffraction(XRD). Two strong excitation bands in the wavelength region of 200- 310 nm were found to be due to the WO4 2. exciton transition and the 4f-5d transition of Tb3+ in K2BaW2O8. The excitation spectrum presents several lines in the range of 310-380 nm; these are assigned to the 4f-4f transitions of the Tb3+ ion. The strong emission line at around 550 nm, due to the 5D4→ 7F5 transition, is observed together with weak lines of the 5D4→ 7FJ(J = 3, 4, and 6) transitions. A broad emission band peaking at 530 nm is observed at 10 K, while it disappears at room temperature. The decay times of Tb3+ 5D4→ 7F5 emission are estimated to be 4.8 and 1.4 ms, respectively, at 10 and 295 K; those of the WO4 2. exciton emissions are 22 and 0.92 μs at 10 and 200 K, respectively.