To accurately control semiconductor nanowires' (NW) physical characteristics defining electronic, optical and sensor applications, it is necessary to understand their potential growth mechanism. In this study, the Ga2O3 NW growth orientation is found to be dependent on their Cu3As catalyst structure via vapor-solid-solid (VSS) mechanism. The Ga2O3 NWs are synthesized by vapor transport method at 700 degrees C below the Cu3As alloy eutectic temperature, which forms a solid structure on top of the NWs. The NWs have relatively uniform diameter of 40-60 nm and prefer to grow along <110> direction. Energy-dispersive X-ray spectroscopy (EDS) and high-resolution transmission electron microscope (HRTEM) data provide strong evidence that the harvested Ga2O3 NWs are epitaxially grown from Cu3As-based (cubic and hexagonal) catalyst seeds. And Ga2O3{110} vertical bar Cubic Cu3As {(2)10}, Ga2O3{110} vertical bar Cubic Cu3As {110} and Ga2O3 {110} vertical bar hexagonal Cu3As {110} have relatively low mismatch compared to other interface lattice planes, providing a key insight into the growth process according to the VSS mechanism. The thermodynamics driven composition changes in the growth process are elaborated in detail. (C) 2021 Elsevier B.V. All rights reserved.