Tungsten oxide thin film in 1-dimensional (1-D) nanostructures shows high photocatalytic activity and the flame vapor deposition (FVD) process is fast and economical method to prepare 1-D nanostructured tungsten oxide thin films of high purity and crystallinity. We investigated the morphology changes of tungsten oxide thin film prepared by FVD process for various process variables such as total gas flow rate, flame temperature and substrate temperature. For the experimental conditions in this study, we confirmed that the selection of suitable total flow rate is a key factor for 1-D nanostructure growth in fuel-rich condition. As we increase the flame and substrate temperatures, the longer and thinner 1-D nanotubes were obtained, which have the advantages of high surface area and shorter diffusion length of proton for the application to photoelectrochemical water splitting. This study would provide the basic information for the design of FVD process to prepare 1-D nanostructures in future. (C) 2019 The Society of Powder Technology Japan. Published by Elsevier B.V. and The Society of Powder Technology Japan. All rights reserved.