Herein, we report an in situ reduction process of GO to rGO on Ni foam during deposition of Co3O4 nanoflakes via ammonia evaporation technique followed by thermal treatment. The synthesis procedure and the design of electrode make it very promising for supercapacitor application. The characteristic electrochemical properties indicate the ‘battery’ type material and supercapattery performances were investigated thoroughly. The electrode exhibited considerably high specific capacity of 1328 C g−1 at 2 A g−1 current density and showed good stability compared to Co3O4 nanoflakes deposited on bare Ni foam. The performance as asymmetric supercapacitor in a two-electrode configuration of Co3O4-rGO/Ni foam also revealed high specific capacitance of 80 F g−1 at current density of 0.1 A g−1 and excellent stability with 94.5% capacity retention after 10,000 cycles. A considerably high energy density of 20 Wh kg−1 at power density of 1200 W kg−1 was achieved for Co3O4-rGO/Ni foam based asymmetric device, confirming the material as a potential candidate for supercapacitor application.