This paper reports the preparation and characteristic property of a new nanocomposite gold cluster with fullerene as a carbon nanocluster, C-60-Au nanoparticles, together wit h the first account of electrochemical comparison of the C-60-Au nanoparticle films and the self-assembled monolayers of C-60-thiol 1 on gold electrodes. Octanethiol-stabilized gold nanoparticles were treated with a fullerene C-60-terminated alkanethiol. (1) to give new fullerenethiol-functionalized gold nanoparticles (C-60-Au nanoparticles) of 2 nm diameter with a very narrow size distribution. Immersion of a gold electrode in a solution of C-60-Au nanoparticles deposited the colloid films of them on the electrode surface which showed two distinct reversible reduction/oxidation waves and significant electrochemical stability. The C-60-Au nanoparticle films were firmly immobilized on the planar electrode by a simple self-assembly method without use of terminal ligand like bifunctional aminosiloxane or mercaptosiloxane. The electrochemical responses for the C60-Au nanoparticle films and self-assembled monolayers of C-60-thiol 1 adsorbed on gold electrodes are significantly different.