The combustion and chemical decomposition techniques were used to synthesize Y(2)O(3) nanophosphors that are high quality powders as promising materials for the next generation of the display technology. Combustion technique focused on an exothermic reaction between Yttrium nitrate and glycine as fuel. The thermal decomposition technique (to our knowledge, a new technique used to synthesize Y(2)O(3) nanocrystalline phosphors) is based on the thermal decomposition of Yttrium alginate gels. The gels in this technique were produced in the form of beads by ionic gellation between a yttrium solution and sodium alginate. Both the wet beads and the Y(2)O(3) powders obtained by using the former technique were annealed at 600, 800 and 1000 degrees C for various annealing times. The products were characterized by X-ray diffraction (XRD) and the crystal size distribution of each product was measured by BET technique. The results explicitly illustrate that the size of the nanocrystalline Y(2)O(3) phosphors is influenced by the technique, annealing temperature and the duration of the annealing process. We found that the size of the nanocrystalline Y(2)O(3) phosphor varies from a 9nm to about 200nm nanometers.