We report in situ scanning tunneling microscopy (STM) results of underpotential deposition (UPD) of copper at well-ordered Pt(lll) and Rh(lll) electrodes in sulfuric acid solutions. Cyclic voltammograms of Pt(lll) at 1 mV/s in 0.05 M H2SO4 and 5 mM CuSO4