Hierarchical NiS microflowers were synthesized by a facile two-step method. Electrochemical measurements results show that the NiS owns the much high Cm and long cycle life. Display omitted •New hierarchical NiS microflowers with high capacitance performance were prepared.•Specific capacitance of NiS is up to 1122.7F·g−1 at current density of 1A·g−1.•Capacitance retention of NiS electrode after 1000 galvanostatic charge-discharge cycles is 97.8%.•NiS//AC delivers an energy density of 31Wh·kg−1 at a power density of 0.9kW·kg−1. In this work, the hierarchical NiS microflowers were synthesized using Ni(OH)2 as precursors through sulfuration process. The microstructure and chemical composition of as-prepared NiS was confirmed by means of SEM, TEM, XRD, BET and XPS. The SEM analysis results demonstrated that the NiS microflowers were composed of hierarchical nanoplates, and its surface was much rougher compared to that of Ni(OH)2 templates after sulfidation. Electrochemical characterization revealed that NiS presented high specific capacitance in 3M KOH electrolyte (1122.7F·g−1 at current density of 1A·g−1) and good electrochemical cycling stability (97.8% of the specific capacitance is retained after 1000 charge-discharge cycles at current density of 10A·g−1). Furthermore, an asymmetric supercapacitor, NiS as the positive electrode and activated carbon as the negative electrode, delivered high energy density of 31Wh·kg−1 at power density of 0.9kW·kg−1 under operating voltage window of 1.8V.