Abstract A series of nanocrystalline rare earth doped alkaline earth sulphates, MSO 4: xEu 3+ (M=Ca,Sr,Ba; x=0.001–0.005), have been prepared by co-precipitation method. Their crystal structures and luminescent properties with and without γ-ray irradiation are compared. It was found that their crystal structures have not changed, but their lattice parameters with irradiation become smaller than those without irradiation. On the other hand, the characteristic emissions of both Eu 3+ and Eu 2+ are observed in the same nanocrystals with γ-irradiation. The differences in their crystal structures and luminescent properties are also discussed.