Supercapacitors are one of the most important methods of energy storage due to features such as high power density, fast charge–discharge rate and long cycle lifetime. In this research, a thermally reduced graphene oxide/polymelamine formaldehyde nanocomposite (TRGO/PMF) was synthesized through a polymerization method. Then, scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction and infrared spectroscopy were used to characterize the TRGO/PMF nanocomposite. Finally, the supercapacitor behavior of the synthesized TRGO/PMF nanocomposite was investigated using cyclic voltammetry, galvanostatic charge–discharge, and electrochemical impedance spectroscopy. The TRGO/PMF nanocomposite shows a 2271 F g⁻¹ specific capacitance at a current density of 1.0 A g⁻¹. Moreover, the stability of the electrode was studied after 5000 cycles, which revealed 91% of the initial capacitance.