A porous network MnO2-poly(5-cyanoindole) composite (MnO2/PCIn) was prepared by a two-step electrochemical method. Since the porous network PCIn film validated by SEM acted as a 3D-random matrix, PCIn film provided an environment to disperse MnO2 nanoparticles and prevented the aggregation of MnO2 nanoparticles. As the active electrode material for supercapacitor, the specific capacitance of MnO2/PCIn/GC reached 322.5 F g(-1) at 8.3 A g(-1), which was higher than that of MnO2 (247 F g(-1)) electrodeposited on the bare glassy carbon electrode. The energy density of MnO2/PCIn/GC reached 36.1 Wh kg(-1) at a high power density of 12.5 kW kg(-1). These results indicated that the presence of PCIn film improved the specific capacitance and charge/discharge cycling stability of MnO2. (C) 2014 Elsevier Ltd. All rights reserved.