Nanostructured nickel oxide (NiO) thin films were prepared using spray pyrolysis technique over cleaned glass substrate with nickel (II)-acetate tetrahydrate and nickel chloride as precursor. The substrate temperature during deposition is varied between 473 and 523 K to study the influence of temperature over the structural and electrical properties of NiO thin films. The structural analysis of NiO thin films were carried out using X-ray Diffraction (XRD) technique and it is observed that the films are highly crystalline with face centered cubic structure. The surface morphology of NiO thin film samples was analyzed using Field Emission- Scanning Electron Microscope (FE-SEM). The sensing behavior of nanostructured NiO thin films towards various concentrations of ethanol was studied and reported.