Cu(OH) 2 cluster-modified TiO 2 (Cu(OH) 2 /TiO 2 ) photocatalysts were prepared by a simple precipitation method using Degussa P25 TiO 2 powder (P25) as a support and copper nitrate as a precursor. Low-power ultraviolet light emitting diodes (UV-LEDs) were used as the light source for a photocatalytic water splitting reaction. The prepared samples show especially high photocatalytic H 2 -production activity from aqueous solutions containing ethylene glycol as sacrificial reagent even without a Pt co-catalyst. The optimal Cu(OH) 2 loading content was found to be 0.29 mol%, giving an H 2 -production rate of 3418 mmol h À1 g À1 with a quantum efficiency (QE) of 13.9%, which exceeded the rate on pure TiO 2 by more than 205 times. This high photocatalytic H 2 -production activity is attributed to the presence of Cu(OH) 2 clusters on the surface of the TiO 2 . The potential of Cu(OH) 2 /Cu (Cu(OH) 2 + 2e À ¼ Cu + 2OH À , E o ¼ À0.224 V) is slightly lower than conduction band (À0.26 V) of anatase TiO 2 , whilst being higher than the reduction potential of H + (2H + + 2e À ¼ H 2 , E o ¼ À0.000 V), which favors the electron transfer from the CB of TiO 2 to Cu(OH) 2 , and the reduction of H + , thus enhancing photocatalytic H 2production activity. This work not only shows a possibility for the utilization of low cost Cu(OH) 2 clusters as a substitute for noble metals (such as Pt) in photocatalytic H 2 -production, but also for the first time exhibits a facile method for enhancing H 2 -production activity by using hydroxide as a co-catalyst .