A single-phased color-tunable phosphor Ca3Y (PO4) 3:Eu2+/Sm3+for WLED was prepared by a conventional solid-state reaction method.X-ray diffraction confirms that the as-prepared samples were single phase Ca3Y (PO4) 3 phosphors.The obtained phosphors exhibit a strong excitation band between 250 and 450 nm, matching well with the dominant emission band of UV light-emitting-diode (LED) chip.In order to tune the emitting color of Ca3Y (PO4) 3:Eu2+phosphor, Sm3+ions were co-doped in.Under 405 nm excitation, Eu2+and Sm3+ions are co-activated so as to produce white light.Meanwhile, the emitting color can be tuned from blue-green to white and eventually to orange-red by precisely controlling the ratio of Eu2+to Sm3+.A correlated color temperature (5 058 K) of the sample with white region was calculated, which shows its suitable application for indoor lighting also.Moreover, we also certify the existence of energy transfer from Eu2+to Sm3+via electric dipole-dipole interaction.