Cu nanoparticles (NPs) were deposited on UV-irradiated TiO(2) in an aqueous solution containing Cu(CH(3)COO)(2) and ethanol by a photocatalytic reaction. Cu NPs on TiO(2) exhibit an extinction (= absorption + scattering + reflection) peak due to localized surface plasmon resonance at around 600 nm initially. The density and size as well as the extinction of Cu NPs increase during the deposition, accompanied by a slight redshift of the peak. Eventually, TiO(2) is mostly covered with coalesced Cu NPs that exhibit a spectrum less characteristic of Cu NPs, but more characteristic of a Cu layer.