(GdxY1-x)(2)O-3:Eu [x=0, 0.25, 0.5, 0.75, 1.0] phosphor particles with 6 at.% Eu dopant of total concentration were prepared using spray pyrolysis. The effects of composition on the morphology, crystallinity, and photoluminescence characteristics of composite particles were investigated. The morphological control of (GdxY1-x)(2)O-3:Eu particles in spray pyrolysis was also attempted by using colloidal and aqueous solutions. The particles prepared from colloidal solutions containing small amounts of Gd or Y hydroxy carbonate sol as seed material had spherical and filled morphology after the post-treatment at high temperature. On the other hand, the (GdxY1-x)(2)O-3:Eu particles prepared from aqueous solutions were hollow and porous after post-treatment in all compositions. Particles prepared from colloidal solutions had photoluminescence emission intensities higher than those of particles prepared from aqueous solutions.