Hierarchical hybrid microarchitectured 3D/1D titanium oxide (TiO2) films were developed by one-step surfactant-free hydrothermal method over TiO2 seeded FTO substrates. The TiO2 films synthesized from hydrothermal method at growth temperature 180 degrees C were dried at room temperature and then heat treatment at 70 degrees C, 150 degrees C, 250 degrees C, 350 degrees C and 450 degrees C formed hierarchical hybrid microarchitectural structures. X-ray diffraction and Raman spectral results of the prepared TiO2 hierarchical hybrid microarchitectured films confirmed the formation of single phase rutile tetragonal TiO2 system. Scanning electron microscopy results revealed that the heat treatment at various temperatures effectively modified the surface morphology of hydrothermally grown 3D/1D TiO2 hierarchical hybrid microstructures. The UV-vis and photoluminescence spectral results of the heat treated TiO2 films revealed modification in the bandgap energy and the electron-hole pairs recombination rate respectively when compared with that of the pristine film. The photoelectric measurements revealed that the heat treated film at 450 degrees C exhibited the relatively higher photocurrent density of 2.68 mA/cm(2) and applied bias potential efficiency of 2.91% as compared with all other heat treated and pristine films. (C) 2018 Elsevier B.V. All rights reserved.