Nanostructured Aluminium (Al) doped Zinc Oxide (ZnO) was prepared by sol-gel spin-coating method to fabricate ZnO-based sensors. The oxygen-sensing characteristics were studied by varying the gas flow rate at room temperature. The electrical and structural properties of the films were carried out using current-voltage (IV) measurement, Atomic Force Microscopy (AFM) and Field Emission Scanning Electron Microscopy (FESEM), respectively. The porous nanostructures exhibited good sensitivity, of 73%, in the presence of 50 sccm of O 2 flow rate. From this study, it is known that, ZnO thin film that was observed to have porous structure might enhance gas sensing performance.