A novel BaSi3Al3O4N5:Eu2+ blue phosphor has been developed for the first time. Rietveld refinements of XRD data indicate that BaSi3Al3O4N5 crystallizes in the monoclinic space group P2(1)/m. This phosphor exhibits comparable photoluminescence intensity with that of commercial BaMgAl10O17:Eu2+ blue phosphor under vacuum ultraviolet (VUV) and near-ultraviolet (NUV) excitation. Furthermore, it shows excellent thermal and chemical stabilities, high quenching temperature, and higher converting efficiency under NUV excitation. The excellent photoluminescence and stability have been analyzed in terms of the stiff crystal structure of BaSi3Al3O4N5. This phosphor could be a promising blue candidate for light-emitting diodes and plasma display panels. (C) 2011 The Electrochemical Society. [DOI: 10.1149/1.3590259] All rights reserved.