Heterogeneous Cu catalysts are widely used in photocatalytic hydrogen generation. The typical working mode includes the transfer of photo-induced charges from a semi-conductor to CuO which itself is reduced to Cu2O to initiate the catalytic cycle. In this contribution a photosensitizer (dye), excited by visible light absorption, was used to transfer an electron to the CuO which after reduction catalyzes the water reduction to hydrogen. Several copper(II)-catalysts on high surface silica were prepared by impregnation or precipitation and applied in photocatalytic water reduction. The best catalyst CuO(Cl0.1)/SiO2, synthesized via incipient wetness impregnation of CuCl2 in MCM-41 and a following precipitation with NaOH, achieved a 6 times higher activity (1702 mmol h(-1) g(-1)) compared to a previously investigated copper system (280 mmol h(-1) g(-1) for CuI) under the same reaction conditions. All materials were fully characterized by XRD, TEM and N-2 sorption and further by magnetic resonance and X-ray methods EPR, ASAXS and XAS. In situ measurements evidenced a reduction of the initial Cu(II)-species, which confirms the (proposed) photocatalytic mechanism. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.