A high-speed, solid-state circuit breaker is capable of interrupting high DC currents without generating an arc, and it is maintenance-free. Both the switch and the tripping unit are solid-state, which meet precise protection requirements. The high-speed, solid-state DC circuit breaker uses an emitter turn-off (ETO) thyristor as the switch. The ETO thyristor has an anode, a cathode and first, second and third gate electrodes. The anode is connectable to a source of DC current, and the cathode is connectable to a load. A solid-state trip circuit is connected to the first, second and third gate electrodes for controlling interrpution of DC current to the load by turning off said ETO thyristor.