A porous nanowall Co3O4 film is prepared by a facile cathodic electrodeposition. The as-prepared porous nanowall Co3O4 film shows a net-like porous structure with huge porosity. The porous network is made up of free standing interconnected Co3O4 nanoflakes with a thickness of 20nm. As cathode material for pseudocapacitors, porous nanowall Co3O4 film exhibits weaker polarization, higher electrochemical reactivity and better cycling performance as compared to the dense Co3O4 film. The specific capacitance of porous nanowall Co3O4 film is 325Fg−1 at 2Ag−1 and 247Fg−1 at 40Ag−1, respectively, much higher than that of the dense Co3O4 film (230Fg−1 at 2Ag−1 and 167Fg−1 at 40Ag−1). The better pseudocapacitive performances of the porous nanowall Co3O4 film are attributed to its highly porous morphology, which provides large reaction surface and short ion diffusion paths, and relaxes the volume change caused by the reaction during the cycling process.