Gd2O3:Eu phosphor particles of spherical and filled morphology were prepared by spray pyrolysis. Morphology control of Gd2O3:Eu phosphor particles in spray pyrolysis was attempted by using colloidal and aqueous solutions. The particles prepared from colloidal solutions containing small amounts of gadolinium hydroxy carbonate sol as seed material had a filled morphology before and after the post treatment; whereas the particles prepared from aqueous solutions were hollow and the structure was broken after post treatment at 1200 degrees C. The particles prepared from colloidal seed solution with 250 nm sol had a spherical and filled morphology with a clean surface; the particles prepared from colloidal seed solution with 70 nm sol had a collapsed spherical shape. The particles prepared from colloidal and aqueous solutions had similar photoluminescent intensities. (C) 2000 The Electrochemical Society. S0013-4651(99)05-06 1-2. All rights reserved.