Sr2Si(O1-xNx)(4):Eu2+ (SSON) powders were prepared by a solid-state reaction method and their structural and luminescent properties were investigated. The X-ray diffraction patterns of SSON exactly coincided with those of alpha'- and/or beta-Sr2SiO4 phases, whereas the luminescent spectral properties of SSON were completely different from those of Sr2SiO4:Eu2+ powders, showing broad excitation spectra and strong red-shift of the emission spectra (green to red) due to Eu-N bonds that caused the nephelauxetic effect and strong crystal field. When M2+ ions (Mg2+, Ca2+, Ba2+) were partly substituted for Sr2+ ions, the emission spectra apparently showed red-or blue-shift of the emission, depending on the relative ionic sizes of the M2+ ions and the nature of the Eu2++ sites, i.e., Eu(I) or (II). (C) 2012 The Electrochemical Society. [DOI: 10.1149/2.062205jes]