PbO2 nanowires were obtained by template electrodeposition in polycarbonate membranes and tested as positive electrode for lead-acid battery. Nanowires were grown on the same material acting as current collector that was electrodeposited too. The nanostructured electrodes were assembled in a zero-gap configuration using commercial negative plate and separator. Cell performance was tested by galvanostatic charge/discharge cycles in a 5 M H2SO4 aqueous electrolyte. PbO2 nanostructured electrodes were able to deliver at 1C rate an almost constant capacity of about 190 mAh g−1 (85% of active material utilization), close to the theoretical value (224 mAh g−1). The nanowire array provides a very large surface area (about 70 times higher than the geometrical one) that enhances the specific capacity of the battery. SEM images of the as-prepared and cycled electrodes showed that nanowires morphology changes significantly after the initial cycles. Change of morphology led to the formation of very spongy structure, characterized by the presence of macro-voids, which ensured penetration of the electrolyte in the inner areas of the electrode. Besides, PbO2 nanowires showed a very good cycling stability, maintained for more than 1000 cycles. These findings indicate that this new type of electrode might be a promising substitute of positive plates in lead-acid battery.