A novel tube-in-tube nanostructure of MnO2@TiO2 hybrid arrays has been obtained by a facile and controllable chemical bath deposition method. Scrutiny on the hybrid arrays indicates that the chemical bath deposition method favors the growth of the MnO2 nanotubes with different diameter which can modulate the oxygen evolution reaction (OER) activity as well as bandgap width of the hybrid. In terms of OER activity, onset potential (E-s) shifts negatively from 0.698 V (vs.Ag/AgCl) of pristine titania nanotube arrays (TNAs) to 0.501 V of the hybrid loaded with 26.6%wt MnO2, and the current density on the hybrid electrode can be significantly enhanced up to 20.87 mA/cm(2), almost 97 times higher than that on TNAs electrode (0.214 mA/cm(2)). Optical absorption measurement suggests that the bandgap width (E-g) can be tuned by loading MnO2 onto the TNAs implying interaction between the MnO2 and TNAs. The MnO2@TiO2 hybrid nanotube arrays may find promising potential in electrochemical water splitting, photocatalysis, thermocatalysis and other sustainable energy applications. (C) 2018 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.