Abstarct: Gas sensors are devices that can convert the concentration of an analyte gas into an electronic signal. Zinc oxide (ZnO) is an important mextal oxide semiconductor which has been indicated good gas sensitivity. In this experimental investigation zinc oxide nanostructured thin films synthesized by spray pyrolysis method and were characterized by their various physical properties including: morphological, structural, optical, electrical properties also their gas detecting properties. In this study we have used the Field Emission Scanning Electron Microscopy (FESEM), X-ray diffractometer (XRD), UV-Vis spectrophotometer, I-V measurement apparatus and Gas Sensing Reactor (GSR). In this research work we have studied not only the effect of doping effect (ZnO:Al and ZnO:Sn) but also the effect of zinc source material (zinc chloride, Zinc nitride and zinc acetate) in fabricating pure ZnO thin laxyers leading to alcohol (methanol, ethanol and propanol) gas detecting properties. We found all samples have nanostructure features with polycrystalline structure in wurtzite phase with (002) preferred orientation. It is shown that surface morphologies, crystallite sizes and electrical properties of the films have crucial effect on their gas sensitivities in low gas concentrations of 200-1000 ppm.