Facile fabrication of a modified electrode with gold nanoparticles and a tris (2,2 ' -bipyridine) ruthenium(II)-viologen linked thiol (RuVS) is described. First, the gold nanoparticles (14 +/- 1 nm) were precipitated onto the gold electrode in an aqueous solution. Then, this electrode was immersed into a acetonitrile solution containing RuVS, to immobilize it via Au-S bonding. Scanning electron micrographs show agglomeration and island formation of the gold particles on the electrode and 1-3 mum thickness of the deposition. In cyclic voltammetry, a redox couple due to one-electron reduction of the viologen moiety was clearly observed and its intensity increased with increasing the extent of deposition. The anodic photocurrent from the modified electrode ascribed to ruthenium-complex-sensitized redox cycles was clearly observed and was more than 15-fold larger as compared with that of the flat electrode (without gold particles).