A Reduced reduced graphene oxide (RGO)-gold (Au) nanoparticle (NP) nanocomposite was synthesized by simultaneously reducing the Au ions and depositing Au NPs on onto the surface surface of the RGOsRGO simultaneously. To facilitate the reduction of Au ions and the generation of oxygen functionalities for anchoring the Au NPs on the RGOsRGO, ultrasound irradiation was applied to the mixture of reactants. The functional groups were investigated with FT-IR spectra. From the Raman and XPS spectra, the oxygen groups were identified as hydroxyl, epoxy, and carboxyl groups, the same as the one from graphene oxide (GO). As a result, the dense and uniform deposition of nanometer-sized Au NPs with nanometer size was observed on the RGO sheets sheet was observed with from the TEM imagesimage. The Oxygen oxygen functional groups that formed on the surface surface of the RGOs RGO seemed to have served serve as links for Au NPs NP attachment, through the electrostatic attraction of Au ions. Hybrid materials could thus be produced in a short time, with a high yield, by via ultrasound application. Besides, it ultrasound application could can readily take goldAu- binding- peptide (GBP)-modified biomolecules, readily implying its possibility in possible biological applications.