Se@CdSe nanocables and CdSe nanotubes with diameters of around 50 nm (see Figure) can be directly synthesized via a template-engaged approach in aqueous solution. The walls of these nanotubes are composed of CdSe nanoparticles 5-10 nm in size. It is believed this approach can be potentially extended to process many other chalcogenides into tubular nanostructures.