Potassium-dibenzo-18-crown-6 complex cation was used as carrier for the uphill transport of mercury as [Hg(SCN)(4)](2-) complex anion through a chloroform membrane system. By using 0.2 mol/L EDTA as a metal ion acceptor in the receiving phase at the optimized pH of 10.0, the amount of mercury transport through the liquid membrane after 120 minutes was 94.2 +/- 0.7%. The selectivity and efficiency of mercury transport from aqueous solutions containing equimolar mixtures of Co2+ Ni2+, Cu2+, Zn2+, Pb-2+,Pb- and Cd2+ ions were investigated. In the presence of 0.05 mol/L EDTA at pH 3.2 as a proper masking agent in the source phase, the interfering effects of Zn2+, Pb2+, and Cu2+ ions were eliminated.