The interfacial composition and the structure of the water/C-12-EOx-C-12.2Br/n-hexanol/n-heptane microemulsion have been investigated by the dilution method. The results showed that C-12-EOx-C-12.2Br formed a stable water/oil microemulsion with the assistance of n-hexanol. Owing to the relatively large size of the head group, more n-hexanol molecules are populated on the droplet surface than in the C-12-2-C-12. 2Br system. The radius of the water pool of the C-12-EO3-C-12.2Br system is not as sensitive to W-o as in the C-12-2-C-12.2Br system. Another feature of the present system is that its droplet size is considerably smaller than that of the C-12-2-C-12.2Br system, and also those of the CPC and CTAB systems at relative high water content. This provides a potential application for the synthesis of nanoparticles with small size. (c) 2007 Elsevier Inc. All rights reserved.