Nanostructured Co3O4 was prepared via a simple two-step process: cathodic electrodeposition of cobalt hydroxide from additive free nitrate bath and then heat treatment at 400 degrees C for 3 h. The prepared oxide product was characterized by powder X-ray diffraction, infrared spectroscopy, surface area measurement, scanning electron microscopy, and transmission electron microscopy. Morphological characterization showed that the oxide product was composed of porous nanoplates, and BET measurement displayed that the oxide plates have the average pore diameter and the surface area of 4.75 nm and 208.5 m(2) g(-1), respectively. The supercapacitive performance of the nanoplates was evaluated using cyclic voltammetry and charge-discharge tests. A specific capacitance as high as 393.6 F g(-1) at the constant current density of 1 A g(-1) and an excellent capacity retention (96.5% after 500 charge-discharge cycles) was obtained. These results indicate that Co3O4 nanoplates can be recognized as high-performance electrode materials.