Hydrogen sorption in conducting polymers was investigated in order to determine their potential as hydrogen storage media. The conducting polymers, polyaniline and polypyrrole, were treated with an acid, which resulted in an exceptionally high hydrogen sorption, 6 and 8 wt% at room temperature and under 9.3 MPa. Both the molecular effect and electrical effects by the conducting polymers appear to play an important role in hydrogen sorption. This paper presents the preliminary results of hydrogen sorption in a conducting polymer along with its characterization by XRD, scanning electron microscopy, TGA, and conductivity measurement using a four-probe method. A possible mechanism for the extraordinarily high hydrogen storage is suggested. (c) 2006 Elsevier B.V. All rights reserved.