Eu2+-activated Sr2Si5N8 red phosphor for white light-emitting diodes was successfully synthesized by an innovative, simple and efficient synthetic process, direct gas-reduction and nitridation of the homogeneous oxide precursor of the SrO-SiO2-Eu2O3 system in the flowing NH3 and CH4 mixture gas. The phase purity, morphology, and luminescence properties were investigated. The synthesized powders have a pure Sr2Si5N8 phase and consist of fine, sub-micrometer-sized particles. Under the blue light excitation, Sr2Si5N8:Eu2+ phosphor shows excellent luminescence properties, such as high emission intensity, high quantum efficiency, and very low thermal quenching, which is comparable to those of phosphors fabricated by the solid-state reaction method. (C) 2008 The Electrochemical Society. [DOI: 10.1149/1.2999278] All rights reserved.