The nanoscale aluminum bowls were derived from the porous alumina and were used as the flexible nanoscale reactors for the preparation of nanoparticles. Both single source precursor and preprepared nanoparticles were induced in the nanobowls by melting the precursor/polymer films spin-coated on aluminum nanobowls for the formation of nanostructural composites in the nanobowls. We have prepared a single nanoparticle or just a small number of metal(e.g. Pt) nanoparticles or semiconductor nanoparticles(e.g. CdSe or CdSe/ZnS core-shell nanostructures) in the nanobowls.