A novel CaWO4/alkali-activated blast furnace slag-based cementitious composite (ASCC) was synthesized and used as an excellent photocatalyst for production of hydrogen by water splitting. XRF, XRD, BET, UV-vis DRS and PL were used to characterize the component, microstructure and optical properties of CaWO4/ASCC. The XRD results showed that the CaWO4/ASCC composite was composed of the matrix of calcium silicate hydrate (CSH) and the active phase of CaWO4 with mean particle size of 11.5 nm. The UV-vis DRS absorption band was red-shifted with the increase of loading amount of CaWO4. The 5CaWO(4)/ASCC composite exhibited the highest amount of hydrogen production of 50827 mu L/g under simulated solar irradiation for 6 h. As comparison with NH4+/ASCC, The excellent photocatalytic activity of 5CaWO(4)/ASCC composite was attributed to the synergistic effect of the active components of CaWO4, TiO2 and the matrix of CSH. A mechanism of generation H-2 was suggested in the paper. (C) 2016 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.