In this study, a novel zero voltage zero current transition (ZVZCT) bidirectional DC-DC converter is proposed by employingcoupled inductors. This converter can turn the main switch on at ZVZCT and it can turn it off with zero voltage switching (ZVS)for both the boost and buck modes. These characteristics are obtained by using a simple auxiliary sub-circuit regardless of thepower flow direction. In the boost mode, the auxiliary switch achieves zero current switching (ZCS) turn-on and ZVS turn off. Due to the coupling inductors, this converter can make further efficiency improvements because the resonant energy in thecapacitor or inductor can be transferred to the load. The main diode operates with ZVT turn-on and ZCS turn-off in the boostmode. For the buck mode, there is a releasing circuit to conduct the currents generated by the magnetic flux leakage to the output. The auxiliary switch turns on with ZCS and it turns off with ZVT. The main diode also turns on with ZVT and turns off withZCS. The design method and operation principles of the converter are discussed. A 500 W experimental prototype has been builtand verified by experimental results.