Abstract Novel oscillations of membrane current or membrane potential were observed when the transfer of Na+ from one aqueous solution (W1) containing 0.1 M NaCl to another (W2) in the absence of Na+ through a liquid membrane (LM) containing dilute Na+ was forced by an applied membrane potential or membrane current, respectively. The current oscillation was induced by the addition of acetylcholine in W1, and inhibited by the addition of such hydrophobic ions as tetraalkylammonium ions or glutamate ion in W1. These oscillations were similar to those at biomembranes with so-called “sodium channels” as regards both induction and inhibition, though the liquid membrane system did not contain any channel proteins. The current and potential oscillations were also inhibited by the addition of bovine serum albumin in W2. The mechanisms of the oscillations, the induction and the inhibitions were elucidated by referring to voltammograms for the ion transfer through a membrane as well as those at aqueous/membrane interfaces, and by taking into account the adsorption of Na+ at the LM/W2 interface. Various LM systems which exhibit the oscillations accompanied by transports of ions other than Na+ were also investigated, and the general feature of the oscillations of membrane current or potential is discussed.