Di(2-ethylhexyl) phosphoric acid (D2EHPA) was used as a highly efficient carrier for the transport of molybdenum ions as MoO2(D2EHPA)(4) complex through a carbon tetrachloride bulk liquid membrane. By using H2O2 as a metal ion acceptor in the receiving phase at the optimum HNO3 concentration of 0.5 M, the amount of molybdenum transported across the liquid membrane after 4 hours was 99.5 +/- 0.7%. The selectivity and efficiency of molybdenum transport from acidic solutions containing a competing ion as well as from a multicomponent mixture were investigated. With the exception of W, the interfering effect of the diverse ions tested was negligible. However, in the presence of 0.5 M citric acid as a suitable masking agent in the source phase, the interfering effect of W(VI) ion was completely eliminated.