Herein, we developed a nanostructured Co3O4 and bio-inspired carbon (BIC) composite by a facile hydrothermal reaction as a supercapacitor electrode material. Microstructural analysis revealed that the BIC-Co3O4 composites possessed the hierarchical structure with a microflower shape consisting of thin nano-petals. Due to its characteristic nanostructure, the BIC-Co3O4 electrode exhibited a high specific capacitance of 473 F/g at a current density of 1 A/g. Moreover, the all-solid-state symmetric device with this electrode delivered the energy density of 17 Wh/kg at a power density of 184 W/kg with remarkable cycling stability over 10,000 cycles. (C) 2019 The Korean Society of Industrial and Engineering Chemistry. Published by Elsevier B.V. All rights reserved.