This thesis encompasses the preparation and testing of supercapacitors. Supercapacitors were prepared from the electrodes made of activated carbon as an electrode material. Desired thickness of 100 μm of the electrode was achieved with a coating apparatus. Electrodes are placed in a EL-CELL „combi” cell with a platnium foil as a pseudo-reference electrode. The three-electrode system was used to monitor electrochemical behaviour and charge distribution on the electrodes. Behaviour and charge distribution were monitored in two different electrolytes: tetrabutylammonium tetraflouroborate (Bu4NBF4) and tetraethylammonium tetrafluoroborate (Et4NBF4). Measurements were conducted by constant current charging and discharging of the capacitors trough 2000 cycles. Constant current of 20 mA was applied to cells while the cell potential was limited in the range of 0,1-2,5 V. During measurements the potential of the electrodes was monitored and the characteristics of the supercapacitor were observed. In addition to the galvanostatic charging/discharging with potential limitation a staircase potentiostatic electrochemical impedance spectroscopy was conducted. The obtained results were shown in diagrams comparing the behaviour of the positive and negative electrodes in two different electrolytes. Galvanostatic charging with potential limitation method gave values that show change in the capacitances of positive and negative electrodes as well as the whole cell. From the voltage drop obtained at the start of the discharge the internal resistances could be calculated. Values of internal resistances demonstrate the influence of different conductivities of two electrolytes. During multiple cycles of charging and discharging, capacitance of electrodes rapidly decreases due to the existence of two different types of charge. Characteristics of the electrodes are measured also with staircase potentiostatic electrochemical impedance spectroscopy. The results were shown in Nyquist diagrams which deviate from the ideal impedance response. The reason for the deviation is the position of the pseudo-reference electrode. Nevertheless, it was possible to identify specific regions on impedance diagrams. High-frequency semicircle is an indication of the slow kinetic processes taking place at electrode/electrolyte interfaces. Measurements of impedance at higher number of cycles show a difference between two electrolytes.