CaWO 4 , CaWO 4 :Sm 3? and CaWO 4 :(Sm 3? , Li ? ) nanoparticles were synthesized by the precipitation method with addition of PEG 200. The X-ray diffraction patterns show that the obtained samples have a pure tetragonal phase. The CaWO 4 sample shows an emission peak at 418 nm originating from the charge-transfer transitions within the WO 4 2-complex. CaWO 4 :Sm 3? and CaWO 4 :(Sm 3? , Li ? ) samples show emission peaks originating from the f-f forbidden transitions of the 4f electrons of Sm 3? ions. The charge compensator of Li ? can enhance the emission intensity effectively. It is found that the emission intensity of CaWO 4 :(3 mol% Sm 3? , 4 mol% Li ? ) phosphor is about double that of CaWO 4 :3 mol% Sm 3? phosphor.