In this work, we report the growth of MoO3 nanowires (NWs) by thermal evaporation with the aim of evaluating their use as catalysts for oxygen evolution reaction (OER) in water splitting application. Growth was performed on two different kinds of substrates, Si(100) and Si(111), and at different growth temperatures between 200 and 400 °C. The effect of such experimental parameters on the morphological, structural, and compositional properties was investigated. The deposited materials were characterized by in situ reflection high-energy electron diffraction, scanning electron microscopy, transmission electron microscopy, Rutherford backscattering spectroscopy, and X-ray diffraction. For a growth temperature of 200 °C, a flat and amorphous oxide layer is obtained, while as the temperature is increased, one-dimensional (1D) growth prevails on 2D layer formation. In particular, at 400 °C, the deposited material …