We have developed gas sensors with antimony oxide nanostructured thin films based on a langasite (LGS) substrate and gold electrodes. Nano-trapezoids and nanorods have been synthesized on langasite and gold surfaces, respectively. With gold (Au) catalyst assistance, these nanoscale structures were grown using the thermal evaporation method. The morphology of the as-synthesized nanoscale structures were characterised using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Energy Dispersive X-Ray (EDX). It was observed that the nanorods have a diameter of 30 to 50 nm and a length up to 750 nm. Meanwhile, for nano-trapezoids, the widths are in a range of 150 to 200 nm, heights in a range of 50 to 140 nm and the length is up to 300 nm. The possible mechanism of SbxOy nanostructures formation is discussed in this report. This sensor has been used for hydrogen (H2) sensing. Response and recovery times and device sensitivity have been measured and the results were discussed.