BACKGROUNDWater dosed with hydrazine was used for the generation of H-2 via a photocatalytic process using CdS nanofibers as photocatalysts under blue light irradiation sources. The optimal dose for the highest H-2 production rate was obtained. Ethanol and sulfite/sulfide ions were also tested as hole scavengers. RESULTSCdS is semiconductor capable of absorbing blue light and used as a photocatalyst in H-2 production. The H-2 evolution with low doses of hydrazine was higher in comparison with the others sacrificial electron donors (SEDs). The mechanism of H-2 evolution involves the participation of hydrazine and the positive holes photogenerated on CdS photocatalysts. CONCLUSIONH2 is generated from the water-hydrazine solution in an O-2-free system. Hydrazine in aqueous solution is photodecomposed by the holes, whereas H+ is reduced to produce H-2 by the reaction with the conduction band electrons. Hydrazine as a sacrificial electron donor is better than the other reagents. (c) 2016 Society of Chemical Industry