In this work, ultra-small Cu(2)O nanoparticles have been loaded on TiO(2) nanosheets with {001} facets exposed through a one-pot hydrothermal reaction. These Cu(2)O nanoparticles are well-dispersed on TiO(2) nanosheets with narrow size distributions and controllable sizes from 1.5 to 3.0 nm. Through XRD, TEM, N(2) absorption-desorption isotherms and UV-vis diffuse reflectance spectra, the Cu(2)O/TiO(2) nanosheets show similar phase structures, morphologies, pore structures as compared to pure TiO(2) nanosheets. Due to the loading of ultra-small Cu(2)O nanoparticles, heterojunctions are formed between Cu(2)O and TiO(2), which favors the efficient separation of photo-generated electrons and holes. Caused by the electron transfer from Cu(2)O to TiO(2), Cu(2)O/TiO(2) nanosheets show excellent visible-light activity, about 3 times that of N-doped TiO(2) nanosheets with {001} facets exposed. Furthermore, charge transfer rate across the interface of Cu(2)O and TiO(2) shows great dependence on the size of Cu(2)O particles. The charge transfer across the interface may be more efficient between TiO(2) nanosheets and smaller Cu(2)O nanoparticles. Therefore, the Ti : Cu = 30 : 1(atomic ratio) sample shows the best activity due to its balance in light harvest and electron transfer rate in the degradation of phenol under visible light.