We report a biotemplating approach to produce porous ZnO nanostructures. In the synthesis, a biotemplate cut from silkworm cocoon was treated with the cetyltrimethylammonium bromide (CTAB) surfactant and soaked in the Zn(NO(3))(2)center dot 6H(2)O solution before it was annealed at similar to 650 degrees C in air. The biotemplate was transformed to a hierarchically interwoven network with hollow fibers composing of ZnO nanometer-sized crystallites. During their formation, micelles of the CTAB molecules attached to the silk transformed the surface charge of the fibers from negative to positive. Consequently, the negatively charged Zn(OH)(4)(2-) ions self-assembled onto the silk fibers through electrostatic interaction. Further annealing eliminated the organic components of the fibers resulted in a porous ZnO network.