Formation of three-dimensional cobalt sulfide hierarchitectures through a mechanism similar to Ostwald ripening has been investigated. Electrochemical measurements reveal that the CoS_1.097nanostructure exhibits superior supercapacitor performances with high specific capacitances (555 F g⁻¹ at 5 mA cm⁻² and 464 F g⁻¹ at 100 mA cm⁻²) and excellent cycle life in 2 M KOH solution.