Abstract: Celestite samples were decomposed by both acid digestion and alkali fusion techniques. Strontium isotopic composition was determined by thermal ionization-mass spectrometry -after purification using cation-exchange resin. Isotopic dilution experiments were also carried out to quantify the strontium content after sample decomposition. Though large difference in strontium recovery exists between the two decomposition techniques, the measured ^87Sr/^86Sr ratios are identical with deviations of less than 0. 000 1. This suggests that both acid digestion and alkali fusion techniques are suitable for strontium isotopic composition measurement of celestite. Relative to alkali fusion techniques, the method of partial digestion of celestite using acids is simpler and easier in purification blank control.