It was found that, ill l suitable pressure range, ethylene Could increase the amount( of solubilized water in reverse micelles of sodium bis-2ethylhexylsulfosuccinate (AOT) in longer chain n-alkanes considerably, where the phase separation was induced by a micelle-micelle interaction mechanism. The microenvironments in the ethylene-stabilized reverse micelles were investigated by the UV-vis adsorption spectra using methyl orange (MO) as a probe. The maximum absorption of MO decreased with the increase of ethylene pressure at constant W-0 Value. Conductivity measurements demonstrated that the percolation temperature of the reverse micellar system increased considerably after compressed ethylene was, added. The results of this work confirm that some small-molecule gases have the function of cosurfactants to stabilize reverse micelles. (c) 2005 Elsevier Inc. All rights reserved.