The direct anodic oxidation electropolymerization of 3,4-ethylenedioxythiophene (EDOT) in IL microemulsions, BmimPF(6)/Tween 20/H2O, has been investigated for the first time. Electrochemical measurements indicated that among water-in-BmimPF(6) (W/IL), bicontinuous (B.C.), and BmimPF(6)-in-water (IL/W) sub-regions in BmimPF6/Tween 20/H2O system, IL/W was the most suitable for the electropolymerization of EDOT, while the electropolymerization did not happen in W/IL. The use of IL microemulsions remarkably reduces the amount of IL, especially for IL/W. UV-vis spectra confirmed the formation of PEDOT. Scanning electron microscopy results demonstrated that nanostructures of compact PEDOT films were still obtained as in pure IL, implying their possible utilization in ion-selective electrodes, ion-sieving films, and matrices for hosting catalyst particles. (C) 2008 Elsevier B.V. All rights reserved.