Alkali-activated granulated blast furnace slag-based cementitious material (AGBFSCM) was synthesized and was firstly used as a novel catalyst for synthesis of hydrogen fuel by photocatalytic decomposition of water. X-ray diffraction (XRD) and field emission scanning electron microscope (FESEM) results indicated that there are two kinds of principally mineralogical phases of calcium silicate hydrate (CSH) and calcium aluminate hydrate (CAH) with mean particle size about 50 nm. The AGBFSCM specimen showed excellent H-2 evolution in amount of 51,697 mu mol/g under the irradiation of solar simulation source for 6 h due to the synergistic effect of mesoporous AGBFSCM framework and natural oxide semiconductors of Fe2O3 and TiO2 existed in AGBFSCM matrix. (C) 2013 Elsevier Ltd. All rights reserved.