Safety is the most important concern for hydrogen production, transportation and storage. A hydrogen sensor based on (004) oriented anatase TiO2 thin film is fabricated with high density and specific orientation by introducing a seed layer and an annealing process for the TiO2 thin film. The sensor has a detection limit as low as 1 ppm with a remarkable sensitivity of 17% and fast response and recovery times as short as 5 s and 64 s respectively. Modelling results based on density functional theory indicate that the energy barrier for H-2 dissociation on the (004) surface is about 0.458 eV. Both Ti and O atoms at the TiO2 (004) surface take part in the H-2 dissociation process. The experimental and theoretical results indicate that surface oxygen has played an important role in hydrogen sensing; lowering the density of surface oxygen vacancies is beneficial in promoting hydrogen sensing. (C) 2019 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.