Ba1-x-2y Eux Cey Liy Ga2 S4 phosphor samples were synthesized by a solid-state reaction method. The lattice parameter of the Ba1-x Eux Ga2 S4 phosphor samples was linearly decreased from 12.654 to 12.492 Å, and the main emission wavelength was shifted from 501 to 530 nm with increase of the Eu2+ ion concentration (x) from 0.05 to 0.50. The relative photoluminescence (PL) intensity under 450 nm excitation was increased with increase of the x from 0.05 to 0.25 due to the excitation band extended to the longer wavelength. However, when x>0.30, the PL intensity was decreased due to nonradiative transitions among the Eu2+ ions and the formation of EuGa2 S4 impurity phase. The Commission International de l'Eclairge chromaticity coordinates were also largely shifted from the bluish-green emitting region (x=0.143, y=0.506) to the green emitting one (x = 2.414, y = 0.658) by increasing the x from 0.05 to 0.50. The energy transfer from the Ce3+ ion to the Eu2+ ion enhanced the PL intensity of the Eu2+ ion emission under near ultraviolet and blue excitation. The PL intensity of the Ba0.900 Eu0.050 Ce0.025 Li0.025 Ga2 S4 phosphor sample was higher by 24% than that of the Ba0.95 Eu0.05 Ga2 S4 phosphor sample under 450 nm excitation. © 2008 The Electrochemical Society.