A moderate hydrothermal approach has been developed to synthesize the perpendicular oriented WO3 nanostructure films. The morphology of the WO3 films could be easily controlled by adjusting the applied amount of HCl in the synthesis procedure. The effects of acidic conditions on morphological control were investigated in details, and the formation process of WO3 nanostructures varying from nanoplates to nanorods has been proposed. Both typical platelike and rodlike nanostructure arrays demonstrate better photoelectrochemical performance than other WO3 nanostructures. The WO3 nanoplate arrays showed a superior photocurrent density of about 1.0 mA/cm(2) at 1.6 V vs. RHE, compared to 0.8 mA/cm(2) of the WO3 nanorod arrays. The increased photocurrent can be mainly attributed to the larger active surface area and more effective charge transfer. Approximately 55% improvement in photoelectrochemical catalytic efficiency was obtained by the WO3 nanoplates photoanode in comparison to the nanorods photoanode in a methyl orange degradation experiment. Such results demonstrate the importance of morphology optimization for improving the photoelectrochemical performance. And the method provides a facile and reasonable way for nanostructure design and morphology control of the photoelectrodes in photoelectrochemical devices. (C) 2017 Elsevier B.V. All rights reserved.