The aim of this study is to prepare Au clusters with a mean size (d) of less than 3.0 nm, at whichnonmetallic properties can be expected to appear. Au clusters (d< 3.0 nm) have been formed rapidly (<2min) on TiO2 surfaces by a two-step method consisting of Au(III)-complex chemisorption and subsequentphotoreduction (λex> 300 nm) at temperatures below 25 °C. In the photoreduction of the Au(III) complexto Au0, chemisorbed and physisorbed H2O on the TiO2 surface acts as a reductant. This method also enablesus to produce Au clusters selectively at the UV-irradiated TiO2 surfaces.