The double-layer and redox capacitances of positive and negative activated carbon electrodes in the ionic liquid N-ethyl-N-methylpyrrolidinium fluorohydrogenate (EMPyr(FH)2.3F) were evaluated based on charge–discharge tests, cyclic voltammetry, and ac impedance spectroscopy. The faradaic reactions differ at the positive and negative electrodes, and both reactions contribute to the large voltage dependence of the capacitance observed for electrochemical capacitors fabricated in this study, using EMPyr(FH)2.3F. The most probable redox reaction at the positive electrode is the oxidation of carbon accompanied by absorption of (FH)nF− or F− into the activated carbon species, and the reverse process. At the negative electrode, the most probable process is the redox reaction involving the adsorption of atomic hydrogen generated from (FH)nF− and the reverse process, although the redox reaction involving surface functional groups cannot be ruled out. The total capacitances of the positive and negative electrodes achieved for charging up to 2.5 V at 238 mA g−1 were 290 and 246 F g−1, respectively. The double-layer and redox capacitance contributions to the positive capacitance were 140 F g−1 and 150 F g−1, respectively, whereas the corresponding contributions to the negative capacitance were 130 F g−1 and 116 F g−1, respectively.