Voltammograms for the ion transfer from one aqueous solution (W1) to another (W2) through a liquid membrane (LM) (VITTM) were recorded under various conditions by scanning the potential applied between two aqueous phases and measuring the current between two aqueous phases. A method of analysing the VITTM was proposed based on the comparison of the VITTM with voltammograms at the W1/LM and LM W2 interfaces observed simultaneously with the VITTM. The membrane transport was demonstrated to be controlled mainly by the complementary ion transfers at the W1LM and LMW2 interfaces, when W1, LM and W2 contain sufficient electrolytes. The influence of different ions in LM or W2 on the membrane transport of an objective ion and the change in ion transfer reactions at the W1LM and LM W2 interfaces during the electrolysis under an applied membrane potential were elucidated taking into account the relation among the VITTM and voltammograms at two interfaces. The ion transport through a bilayer lipid membrane (BLM) was found to be analogous to that through an LM when the BLM contains sufficient ions, although the BLM is very much thinner than the LM.