The solar driven photo-electrolysis of water for hydrogen and nanoparticles formation from electrolyte with corresponding metal salts was investigated. The photoanode consisted of a thin layer of silicon nanowires deposited on molybdenum and a platinum wire as the cathode was used. The prepared photo-anodes were stable up to 0.3 V against the saturated Ag/AgCl electrode without any signs of gaseous oxygen evolution. This photo-electrochemical system enhanced the nanoparticle formation during the illumination phase accompanied with lowering the external potential needed. The present results show that hydrogen in statu nascendi is formed during illumination of photoanode, which causes the formation of nanoparticles by reduction of metal salts. During the photo drive electrolysis, hydrogen is stored in/on forming nanoparticles. The size of nanoparticles can be determined by time and an external bias value inserted between the working and platinum electrodes in a classical three electrode system. It was confirmed that the formation of nanoparticles was limited by diffusional processes of hydrogen in statu nascendi in electrolyte, which is in agreement with literature. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.