Photocatalytic studies are primarily focused on the low cost and sustainable materials with suitable bandgap and high surface area. The ultra-fast electron-hole pair recombination and limited light absorptions affect the efficiency of photocatalyst in an adverse manner, which can be unravelled by choosing an efficient combination of photocatalysts and suitable co-catalyst/support materials. The present work explores the combination of low-cost and high potential activated carbon and TiO2 as a nanocomposite, prepared through a one-pot hydrothermal process for hydrogen production under natural solar light irradiation. Among the synthesized photocatalysts, the one calcined at 400 °C for 2 h was found to be the best catalyst, which exhibited 3.5 times higher hydrogen production rate than the pristine TiO2 while tested with water containing 5 vol.% glycerol. Importantly, the optimized nanocomposite was also tested for hydrogen production from simulated seawater under same conditions and it showed a hydrogen production rate of 20,383 μmol g−1 h−1, which is 2.4 times higher than the glycerol water solution. The enhanced hydrogen production rate is due to the reduced bandgap of AC-TiO2 nanocomposite which offered more light absorption in the visible region compared to the pristine TiO2. The XRD, Raman spectroscopy, TEM, and PL analysis were also examined to investigate the crystallinity, purity, morphology, and charge carrier recombination life time of the synthesized catalysts. © 2020 Elsevier Ltd and Techna Group S.r.l.