The one-step synthesis of sub-micrometer-sized (Ca,Mg)5(PO 4)3Cl:Eu, non-aggregated fine chloroapitite blue phosphor powders, from a aqueous precursors through a spray pyrolysis (SP) method, was reported. The results indicate that the increasing Cl ions along a particular direction expand the unit cell of the crystals, resulting in an improvement of crystallinity. The color of particle change from red to blue with increasing Cl molar fractions, implying that the reduction reaction is improved by Cl addition. It is also found that the crystal structure of chloroapatites can become more stable due to the substitution of Ca2+ and Mg 2+, which is smaller in size. The XY coordinated of these apatite phosphors are found to be very close to Nichia's super-bright blue InGaN LEDs.