We study the spatiotemporal dynamics of the potentiostatic electrodissolution of a circular iron electrode in sulfuric acid under conditions involving oscillations between active and passive states. We measure the spatially averaged dissolution rate (the current), and record spatially resolved surface patterns (the growth of a passivating film) with a video camera. As the potential is varied, the O(2) spatial symmetry of a base oscillatory state (high potentials) breaks giving rise to a period-doubled oscillation with apparent Z2+Z2c spatiotemporal symmetry.