With n-hexanol as the cosurfactant, quaternary ammonium Gemini surfactants C 12 -EO x -C 12 · 2Br (x = 1, 2, 3) formed the reverse micelles in n-heptane. The critical reverse micelle concentrations (cmc h ) were determined using the absorption spectrum method with iodine as the probe. All values were less than the corresponding critical micelle concentration (cmc aq ) in aqueous solution, where C 12 -EO x -C 12 · 2Br formed the normal micelles. The cmch increased with increasing x, which was similar to the variation of cmc aq with x. The saturated amount of water solubilizated by the reverse micelles was enhanced by either increasing x or raising the temperature.