Water splitting is an important technique to store solar energy in the simple form of chemical energy, such as hydrogen. Strontium titanate (SrTiO3) is one of the most promising photocatalysts to produce hydrogen gas from water splitting. In this research, an electrospinning technique in combination with sol-gel method was developed to synthesize 3D porous SrTiO3 nanostructures. Different crystallite sizes of SrTiO3-nanofibers (STO-NFs) were produced by varying the synthesis parameters including precursor concentration and calcination temperature. The synthesized nanofibers were characterized using DSC, TGA, XRD, SEM, and TEM. The crystallite size of STO-NFs decreases with increasing precursor concentration (3.03-15.78 vol.%) and gradually increases as the calcination temperature increases within the range of 600-800 degrees C. The photocatalytic activity of different STO-NEs (based on crystallite size) was also evaluated by the amount of H-2 production from water splitting under UV irradiation. The H-2 evolution study demonstrated that the photocatalytic activity of the STO-NFs strongly depends on the crystallite size of the nanofibers, precursor concentration, and calcination temperature. The H-2 production rate increases with increasing crystallite size and temperature, whereas it decreases with increasing precursor concentration. The photocatalytic performance of the STO-NEs was also compared with the commercial SrTiO3 nanoparticles (STO-NPs) after Pt addition as a cocatalyst, where the synthesized nanofibers showed 2 times higher H-2 production rate (1.14 mmol/g-h) than that of the nanoparticles. This synthesis technique provides a good example to produce other inorganic photocatalytic 3D porous structure materials. (C) 2017 Elsevier B.V. All rights reserved.