Au nanoparticles (NPs) with a radius ranging from 4 ∼ 18nm (mostly 11nm) were stably and uniformly hybridized on the surface of reduced graphene oxide (RGO) after co-reduction of Au precursor ions and graphene oxide (GO), to Au atoms and RGO, respectively. The hybridization was provided by dry plasma reduction (DPR) operated under atmospheric pressure and at a low temperature without any toxic chemicals. The structure of the AuNP/RGO nanohybrid was characterized by SEM, TEM, XPS, XRD and Raman spectroscopy. Raman spectra indicated that DPR induced an increase in the degree of clustering of the sp 2 phase in addition to sp 2 bond restoration. Increasing the number of AuNP/RGO layers yielded a decrease in the transmittance and sheet resistance of the AuNP/RGO nanohybrid. A developed electrode based on the AuNP/RGO nanohybrid showed high electrochemical catalytic activity and high conductivity in comparison with the AuNP and GO electrodes. Thus, the AuNP/RGO nanohybrid fabricated by DPR could be an excellent material for a low-cost counter electrode for dye-sensitized solar cells using Co 2+ /Co 3+ redox electrolyte.