We report a photoexcitation of intrinsic plasmon in conductive polyaniline film deposited electrochemically over an interdigitated array, consisting of alternating electrodes on an insulating substrate. Under monochromatic radiation of X-ray source in a photoelectron spectrometer, an additional feature of X-ray photoelectron spectroscopy profiles appears, characteristic of intrinsic plasmon generated in a complex screening mechanism of uncompensated photoholes. A discussion on the implication of percolation conductive networks in conducting polymers is given. The reported effect may be important for the design of novel plasmonic devices, paving the way to a new type of plasmonic devices for biochemical sensing, photonics, nonvolatile memory, etc. (C) 2010 The Electrochemical Society. [DOI: 10.1149/1.3431545] All rights reserved.