For luminance improvement of Y2O3:Eu3+ red phosphor synthesized by spray pyrolysis method without post-heating, the furnace temperature was raised and residence time was extended. Dependence of luminance of the phosphor on reaction temperature and residence time showed a local maximum. When furnace temperature was too high, and/or the residence time was too long, the luminance was reduced because an impurity, Y4Al2O9, was generated. The aluminum originated from the alumina reactor tube. The maximum luminance of the phosphor obtained in this study was 75% of the luminance of a commercial phosphor made by solid-state reaction. (C) 2003 The Electrochemical Society.