The stable sol with a nominal composition SrAl2O4 :(Eu, Dy) for the spin-coated thin film was successfully synthesized by using cheap inorganic starting materials under the appropriate conditions, i.e., the solution concentration containing Al2O3 of 0.2-0.3 mol/L, the pH value of 5-6, with the additive of glycol or glycerol, at the reaction temperature of 80-90 degreesC. The phase-forming processes of SrAl2O4 :(Eu, Dy) gel were determined by the differential thermal analysis, thermogravimetric analysis, and X-ray diffraction. The SrAl2O4 :(Eu2+, Dy3+) phosphor thin films annealed at 1000 degreesC in reduced atmosphere are uniform and crackfree. The phosphor thin films emit 516 nm bluish-green light under the excitation from ultraviolet to visible light, and the afterglow can be seen by eyes after 10 h in the darkroom. (C) 2004 The Electrochemical Society.