Activated carbon-methyl orange-polyaniline (AC-MO-PAn) composites have been synthesized for the first time. The structural properties of the composites have been characterized with nitrogen absorption-desorption, Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS). The electrostatic force between MO molecules and aniline (An) salt is assumed to promote the adsorption of aniline on the surface of AC. On the other hand, the sulfonic groups in MO molecules play a role of dopant and provide active sites for the polymerization of aniline. Although the loading amount and structure of PAn in as-prepared AC-MO-PAn composites and conventional AC-PAn composites are almost the same, the electrochemical measurements indicate that the AC-MO-PAn composites have preferable capacitive performance and are favorable to be used as the electrode materials in supercapacitors. (C) 2012 Elsevier Ltd. All rights reserved.