A "middle phase" microemulsion, which bicontinuously composed of saline and toluene microphases, with sodium dodecylsulfate (SDS) and n-butanol was electrochemically characterized. When electrochemistry was performed in the "middle phase" microemulsion, reversible redox peaks of the Fe(CN)(6) ion in the micro water phase and the ferrocene in the micro toluene phase could be observed simultaneously, although the electrolyte was present only in the water phase.