The physicochemical properties of theα, ω- type (bolaform) surfactant, eicosane-1, 20-bis(triethylammonium bromide) (C20Et6), in aqueous solution have been investigated by means of surface tension, electrical conductivity, dye solubilization, and time-resolved fluorescence quenching (determination of average micelle aggregation number). Using electrical conductivity, the critical micelle concentration of C20Et6was found to be 6.0×10−3mol dm−3and the ionization degree of C20Et6micelle was found to be 0.42. From surface tension measurments, the molecular area of C20Et6at the air-water interface was about twice that of normal type surfactants such as dodecyltrimethylammonium bromide (DTAB). The solubilizing power of micellar solution of C20Et6toward Orange OT was 1.0×10−2mole of dye per mole of surfactant, i. e., slightly smaller than that of DTAB. The micelle aggregation number,N, was found to be 17±2 by time-resolved fluorescence quenching. C20Et6showed a very small temperature dependence ofN, much less than for normal s