Abstract Red-light-emitting phosphors of La 2 Mo 2 O 9 :Pr 3+ and S-doped La 2 Mo 2 O 9 :Pr 3+ were prepared by high temperature solid state reaction. Under the excitation of 450 nm blue light, all samples produced a red emission peak at 650 nm corresponding to the characteristic transition of Pr 3+ ( 3 P 0 → 3 F 2 ). The dependence of Pr 3+ doping content ( x ) on the luminescent intensity was analyzed, and the optimal doping content of Pr 3+ was x =0.07. After a small quantity of sulfur was introduced into the system, the luminescence intensity of phosphors was obviously enhanced. The reasons for the enhancement of luminescence are due to improved crystallization after S doping and the relatively large electronegativity difference between S and Mo. Additionally, the coincidence of the excitation wavelength with the emission of GaN chips may recommend this phosphor system as a potential candidate for use in white light-emitting diodes.