The obtained specific capacitances are much higher than those ZnS (11.3 F g -1 at 0.5 A g -1 ). nanoflowers in between the 2D layers of g-C3N4. GCD analysis was performed in the twoelectrode symmetric configuration at a current density of 1 A g -1 in 2 M KOH electrolyte. The obtained specific capacitance values are174 F g -1 , 64 F g -1 , and 50.22 F g -1 for g-C3N4/MnO2, g-C3N4/SnO2, and bare g-C3N4, respectively and the corresponding energy density values at a constant power density of 1 kW Kg -1 are 6.9, 8.8, and 4.1 W h Kg -1 . The galvanostatic chargedischarge measurements were performed to study the stability performance of the supercapacitor devices for 6000 cycles at a constant current density of 5 A g -1 , which exhibited the cycling stability of 94%, 85%, and 87 % for bare g-C3N4, g-C3N4/SnO2, and g-C3N4/MnO2, respectively. The observed lower stability of the composites compared to bare g-C3N4 is reported to be due to the presence of lower stability of pseudocapacitive transition metal oxides.