A disposable electrode assembly for a portable defibrillator (12) comprises defibrillator electrodes (14), batteries (24) for powering the defibrillator, and a connector (22) for connecting the electrodes and batteries to the defibrillator. The connector has power output terminals (20) for connecting the battery to the defibrillator and high voltage input terminals (20) for applying a defibrillation voltage to the electrodes. The batteries (24) are housed in the connector (22) or mounted on the rear of one electrode.