Hydrothermal reaction at 150 degrees C and pH = 10 for 24 hours crystallized (Gd,RE)(2)(OH)(4)SO4 layered hydroxide sulfate (monoclinic structure; RE = Pr, Tb), from which Gd2O2S:RE (hexagonal structure) green phosphor hexagons were derived via facile dehydration in flowing H-2 at 1200 degrees C. Rietveld refinement of the XRD patterns yielded cell dimensions that confirmed the direct crystallization of solid solution. Photoluminescence (PL) study at room temperature found absolute quantum yields of similar to 25.1% and 28.4%, CIE chromaticity coordinates of (0.145, 0.679) and (0.326, 0.566), and fluorescence lifetimes of similar to 2.36 mu s and 1.21 ms for Pr3+ and Tb3+ under 300 and 275 nm UV excitations, respectively. Temperature-dependent PL analysis (25-200 degrees C) indicated that both the Pr3+- and Tb3+-doped phosphors have favorably good thermal stability and retained similar to 65% and 80% at 100 degrees C and similar to 41% and 47% at 200 degrees C of their initial emission intensities, respectively. The activation energy for the thermal quenching of PL was determined to be similar to 0.221 (Pr3+) and 0.314eV (Tb3+). Cathodoluminescence (CL) found that both the phosphors exhibit increasingly higher emission intensity/brightness at a higher acceleration voltage (up to 7 kV) or beam current (up to 50 mu A) and are stable under electron bombardment in the studied range. Raising beam current was suggested to be more effective to enhance CL.