Microemulsions in a ternary system of bis(N-octylethylenediamine)zinc(II) chloride (Zn(oct-en)(2)Cl-2)/benzene/water were investigated by transmission electron microscopy, atomic force microscopy, infrared absorption spectroscopy, and the Fourier transform pulsed-gradient spin-echo NMR method. W/O microemulsion, sponge, and bicontinuous structures were observed to have formed in the ternary system. At the interface of the benzene and water domains in the bicontinuous structure, hydrocarbon chains of cisoid Zn(oct-en)(2)Cl-2 were arranged, maintaining a 6 Angstrom separation. The diffusion coefficient of water decreased in the following order depending on the water domain size: sponge; bicontinuous; W/O microemulsion structures.