Abstract: The complexation of LiSCN by 4,4'-ditert-butyldibenzo-30-crown-10 was investigated in view of possible isotope effects. In the chloroform/water system, the distribution ratio and single stage separation factor of Li are equal to 0.10 and 1.036, respectively, and the equilibrium of exchange reaction reaches in less than three minutes. 99.2% of Li in organic phase can be stripped down by equal volume of water as organic phase. The solubility of this crown in water is 2.92 ×10-6 M/1 at 25℃.