A facile room-temperature solid-state route is developed to produce Co(OH) 2 /bamboo charcoal composite for the first time. Electrochemical results show that the resulting composite with the bamboo charcoal content of 20wt% can deliver a high specific capacitance of 439Fg −1 at 0.2Ag −1 , which is much larger than that of the bare Co(OH) 2 (294Fg −1 ) and bamboo charcoal (153Fg −1 ), indicating the synergistic effect of Co(OH) 2 and bamboo charcoal. In addition, the capacitance degradation of ca. 5% after 1000 continuous charge–discharge cycles suggests its excellent electrochemical stability. Moreover, the fabrication process proposed here is simple and cost-effective due to the abundance and renewability of bamboo.