Coadsorption of water and anions and IR background shift were observed during the underpotential deposition of Cu on Au (111)in H2SO4 and in HClO4 solutions using attenuated total reflection-infrared spectroscopy. Phase transition of the deposited Cu structures was confirmed by significant frequency shift of the n(S-O) mode from SO43-. Delayed ordering of water to SO43- was found. Only LR background shift was observed for the Pb-UPD process due to an inherently weak interation between Pb and anions. It was rationalized by the effective medium theory assuming a slight change in dielectric constant of the absorbate layer upon chemisorption.