The near-room temperature current-voltage (I-V) characteristics of small structures made from the metal-cluster materialAu55[P(C6H5)3]12Cl6were studied. It is shown that these electron-beam defined structures have highly nonlinear characteristics with features, including a threshold voltage and scaling behavior, which are consistent with Coulomb charging of individualAu55cores in a disordered array. Applied radio frequency signals introduce plateaus in theI-Vcharacteristics, which demonstrates the presence of coherent tunneling in these cluster systems. ©1997 American Institute of Physics.