An adiabatic reversible circuit was designed for charging a Lithium ion capacitor. The duty ratio of the switching transistors is digitally controlled by a microprocessor. A Lithium ion capacitor has the minimum and the maximum operating voltage. Therefore, the charging voltage is set to be in that range. Using this energy storage system, it is clarified from the experiment that the efficiency is 95.5% during charging and also discharging process. Then the total efficiency is 91.2% during one cycle, which is the best value in the proposed stepwise adiabatic charging circuit. Keywords: Adiabatic, Reversible circuit, Lithium ion capacitor, Stepwise charging