Effect of g-C3N4 loading on hydrogen treated TiO2 photocatalyst was studied towards the efficient photocatalytic and photoelectrochemical application. The tailored optical properties and enhanced photoinduced electron-hole separation in crystalline TiO2 (c-TiO2) was achieved by creating an amorphous shell (a-TiO2) around c-TiO2. The a-TiO2/c-TiO2 core shell particles were further modified by g-C3N4 coating, where amorphous a-TiO2 act as an interlayer between g-C3N4 and c-TiO2 nanocrystals. It was observed that photocatalytic degradation of Methylene Blue (MB) and water splitting to produce hydrogen was remarkably increased under visible-light upon coupling of a-TiO2/c-TiO2 core-shell particles with g-C3N4 and results in the best MB degradation performance of similar to 82% in 1 h and water splitting photocurrent density of 450 mu A/cm(2). The results from UV vis absorption study, Fourier transform infrared spectroscopy and electron microscopy, photoluminescence, photoelectrochemical measurements and electrochemical impedance spectroscopy suggest that the improved photoactivity is due to the increased light absorption in visible region and efficient charge separation as a result of effective interfacial electron transfer between g-C3N4, a-TiO2 and c-TiO2 in g-C3N4/a-TiO2/c-TiO2 composite. Copyright (C) 2016, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.