Flame spray pyrolysis has been utilized in order to improve the photoluminescence (PL) intensity of blue-emitting Sr-5(PO4)(3)Cl:Eu2+ phosphor particles for light emitting diode applications. When Sr-5(PO4)(3)Cl:Eu2+ phosphor particles were prepared by conventional spray pyrolysis, the PL intensity was much lower than that of commercial Sr-5(PO4)(3)Cl:Eu2+ phosphor particles. However, Sr-5(PO4)(3)Cl:Eu2+ phosphor particles prepared by the flame spray pyrolysis showed a high PL intensity compared with the commercial one. The morphology and the crystallinity of Sr-5(PO4)Cl:Eu2+ phosphor particles are strongly affected by the flame condition and the post-treatment environment. Sr-5(PO4)(3)Cl:Eu2+ particles prepared by flame spray pyrolysis were of smaller size than commercial ones, although their spherical morphology was not maintained after the post-treatment at 1000degreesC with NH4Cl flux. The addition of NH4Cl flux during post-treatment greatly enhances the PL intensity of prepared Sr-5(PO4)(3)Cl:Eu2+ phosphor particles due to increased crystallinity. It was found that the phosphor particles with larger crystallite size have higher PL intensity regardless of the method of preparation. (C) 2003 The Electrochemical Society.