The Gd2O3 :Eu phosphor particles with high brightness and spherical shape were prepared by spray pyrolysis from the polymeric precursor solutions. The particles prepared from the nitrate precursors had a hollow and irregular structure in the preparation conditions of high concentration, high flow rate of carrier gas, and large size reactor. However, the Gd2O3 :Eu particles prepared from the polymeric precursor solutions obtained from citric acid and ethylene glycol had a spherical and filled morphology. The Gd2O3 :Eu phosphor particles prepared from the polymeric precursors had the higher intensities than that of the particles prepared from the nitrate precursors. The maximum photoluminescent intensity of the particles prepared from the polymeric precursor solution was 146% of that of the particles prepared from the nitrate precursors. The photoluminescent intensity of the Gd2O3 :Eu particles prepared from the polymeric precursor solutions was 120% of that of the commercial Y2O3 :Eu phosphor particles.