A discharge device and method actively discharge a main capacitor in an electric-power system of an electric-drive vehicle. The discharge device comprises a discharge branch of a circuit that is connected in parallel to the main capacitor and includes a discharge transistor that is biased to “conduction” mode when the main capacitor is required to be discharged. A control device is connected to a “gate/base” terminal of the discharge transistor and commands the discharge transistor, biasing the discharge resistor to “conduction” mode when the main capacitor is required to be discharged. The control device includes a safety capacitor that is interposed between the “gate/base” terminal and a power supply and charges when the discharge transistor is in the “conduction” mode, causing a progressive decrease of current at the “gate/base” terminal, until the discharge transistor is biased to the “non-conductive” state.