In this study, a novel facile and rapid method to prepare three-dimensional (3D) flower-like CoS hierarchitectures by microwave assisted heating has been developed. The 3D flower-like CoS architectures are constructed by two-dimensional nanopetals intertwined with each other and the formation mechanism are studied. The pseudo-capacitive properties of the CoS material are evaluated by cyclic voltammetry and galvanostatic charge-discharge tests in 6M KOH solution. A specific capacitance of 586 F g−1 is obtained at a charge-discharge current density of 1 A g−1. The CoS nanostructure exhibits excellent cycling stability and it maintains 91% of its initial specific capacitance after 1000 cycles. It also exhibits excellent rate capability, improved energy density and power density.