Zn1-xSnxO (x=0, 0.05, 0.10, 0.15, 0.20) nanostructures have been grown through the successive ionic layer adsorption and reaction method. The structural, morphological and compositional properties of the nanostructures have been characterized through X-ray diffraction, scanning electron microscope and energy dispersive X-ray analysis, respectively. The NO gas sensing properties of sensors to 20ppb have been systematically investigated in the dark and under UV light irradiation. A Zn0.90Sn0.10O sensor has exhibited the highest response for 20ppb NO gas compared with other sensors. The sensor response has increased from 1.9 to 43% depending on the UV light irradiation for the Zn0.90Sn0.10O sensor. Zn0.90Sn0.10O nanostructure can be used as a suitable gas sensor material for detection of low concentration levels of NO gas.