Carbons derived by pyrolysis of coffee shells treated with ZnCl2 were used as electrode materials in symmetric electrochemical supercapacitors. Scanning electron microscopy showed that the carbon from the porogen-free shells show a flake-like structure,while those from the ZnCl2-treated coffee shells have a loose, disjointed structure with no definite shape. X-ray diffraction studies indicated the presence of small domains of coherent and parallel stacking of the graphene sheets. The average surface area of the carbon was 842 m(2)g(-1). with an average micropore area of 400 m(2) g(-1). Cyclic voltammetric studies suggested a specific capacitance of about 150 Fg(-1). Self-discharge studies on the devices showed a large retention time. (C) 2008 Elsevier B.V. All rights reserved.