Manganese dioxide (MnO2) nanostructures in the forms of thin film and powder had been prepared by two different preparative approaches. There were sol-gel and hydrothermal approaches. In the sol-gel synthesis approach, stable colloidal suspensions of MnO2 were pepared by chemical reduction of permanganate salt. Nanostructured MnO2 thin films were prepared by a self-assembly horizontal submersion process which involved spontaneous assembly of MnO2 nanoparticles in stable colloidal suspension. The films were subsequently deposited directly onto the supporting substrate (stainless steel foils or Ni-coated PET films) under controlled conditions.