In this work, the synthesis and testing of reduced graphene oxide (rGO) and rGO modified with acetylene black (AC) was carried out with the aim of making a supercapacitor and a hybrid supercapacitor. The testing was conducted in a three electrode system using the method of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The modified electrodes contained 10 % and 20 % acetylene black. It was determined that all electrodes show good capacitive properties in Na2SO4 and ZnSO4 solutions. Also, it was possible to precipitate zinc in ZnSO4 solution. Three different concentrations of ZnSO4 electrolyte were used, whereby the best reversibility was achieved in the solution with the highest concentration. The surfaces of the electrodes were recorded with an optical microscope, which indicated that the porosity of the layer increases with the addition of AC. Except the modified electrodes, rGO paper modified with 20 % AC (rGO/20% AC paper) was also successfully prepared in this work. The obtained rGO/20 % AC paper was used as an active material in a supercapacitor containing 0.5 mol dm-3 Na2SO4 electrolyte and in a hybrid supercapacitor containing 1 mol dm-3 ZnSO4 as the base electrolyte. The assembled supercapacitors were tested using the CV and EIS methods. Additionally, they were tested during 1000 charge/discharge cycles. For the supercapacitor, the obtained values of specific capacitance range from 20.15 to 21.62 F g^-1, while the hybrid supercapacitor has slightly higher values, from 28.21 to 31.78 F g^-1. The higher values of the specific capacitance of the hybrid supercapacitor are proof that it has been successfully prepared.