A nanoporous templating substrate, which is an anodically oxidized alumina (AAO) substrate, is employed to form a pseudocapacitor having high stored energy density. A pseudocapacitive material is deposited conformally along the sidewalls of the AAO substrate by atomic layer deposition, chemical vapor deposition), and/or electrochemical deposition employing a nucleation layer. The thickness of the pseudocapacitive material on the walls can be precisely controlled in the deposition process. The AAO is etched to form an array of nanotubes of the PC material that are cylindrical and structurally robust with cavities therein. Because the AAO substrate that acts as scaffolding is removed, only the active PC material is left behind, thereby maximizing the energy per mass. In addition, nanotubes may be de-anchored from a substrate so that free-standing nanotubes having randomized orientations may be deposited on a conductive substrate to form an electrode of a pseudocapacitor.