Nanoparticles strung on nanotubes, like a beaded necklace (see Figure), have been synthesized by a simple low temperature supercritical solution method. That the crystalline spherical Co3O4 nanoparticles on multiwalled carbon nanotubes are a step towards high-density integrated nanometer-scale functional devices is demonstrated by the fabrication of Schottky junction diodes from individual "beaded" nanotubes.