Polyaniline nanotubes are synthesized from manganese oxide templates (see figure and cover). Manganese oxide is used as the physical template and the chemical oxidative initiator for the aniline polymerization. The template can be removed after the reaction, as manganese oxide is reduced into soluble Mn2+ ions. Many morphologies of polyaniline structures, such as nanotubes, spherical tube brushes, and double-shell nanotubes, can be fabricated using this method.