The poor conductivity of polyindole (PIn) is a major factor to limit its application in supercapacitors. To solve the problem, a simple and efficient immersion method designed to obtain a binary nanocomposite, which composed of polyindole hollow nanospheres (PIn-NS) and poly(3,4-ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT:PSS). PIn-NS with diameters of 300-600 nm and shell thickness of about 50 nm were prepared by the chemical oxidative polymerization of indole in the ethanol/H2O miscible solution using ammonium peroxydisulfate (APS) as oxidant agent without any surfactants. The pure PIn-NS modified carbon cloth (PIn-NS/CC) shows a low specific capacitance of 110 F g (1) at 0.5 A g (1) in 1.0 M H2SO4 aqueous solution. By the immersion of PIn-NS/CC in PEDOT:PSS/ethanol solution, the obtained PIn-NS/CC-PEDOT:PSS shows a large improved specific capacitance of 623 F g (1) at 0.5 Ag (1) and good stability with a cycling efficiency of 84.8% after 3000 cycles. The results demonstrate that the electrochemical properties of PIn-NS can be significantly improved with the assistance of PEDOT:PSS as electrically conductive connection. In addition, the symmetric PIn-NS/CC-PEDOT:PSS//PIn-NS/CCPEDOT:PSS supercapacitor showed a high specific capacitance of 161 F g (1) at 0.5 A g (1) and the low equivalent series resistances (ESR) of 4.4 ohm. Therefore, such binary composite is a promising material for application in the next generation high-performance supercapacitors. (C) 2016 Elsevier Ltd. All rights reserved.