Near-edge X-ray absorption fine structure spectroscopy spectra of ethylenedioxythiophene has been recorded in gas phase at the carbon K-edge, sulphur L-edge and oxygen, K-edge. The experimental data has been interpreted with the help of a modified density functional code deMon. The good agreement between the calculated spectra and the measured one allows us to assign all observed resonances. The existence of pi* resonances in both the measured and the calculated OK-edge adsorption spectrum demonstrate that the delocalized pi-system of the thiophene part of the molecule is extended up to the oxygen atoms of the molecule. (C) 2004 Elsevier B.V. All rights reserved.