Nickel based three-dimensional reticulate Ni3S2 was fabricated by a facile hydrothermal method with excellent capacitance after activation when used as electrode materials. Through electrochemical tests in 2 M KOH solution, the Ni3S2 exhibits excellent capacitance performance of 0.647 F cm−2 at 2 mA cm−2. Due to its activation properties, the areal specific capacitance could increase to 6.244 F cm−2 at 2 mA cm−2 (965.1% increment) after 5000 cycles. It has a good capacitance retention ratio of 68.6% at a current density of 20 mA cm−2, and excellent stability with 89.75% retention of its values at 5000 cycles after circulations of 1000 numbers. The results demonstrate that the Ni3S2 is one of promising candidate electrode material for next-generation high performance supercapacitors.