In-doped ZnO thin films with 0%,1%, 3%, 5% and 7% In were deposited by Successive Ionic Layer Adsorption and Reaction (SILAR) method on glass substrates for nitric oxide (NO) gas sensing application. X-ray diffraction (XRD), scanning electron microscope (SEM) and energy dispersive X-ray analysis (EDAX) were used to evaluate the effect of In doping concentrations on properties of the films. The XRD study clearly shows the existence of the polycrystalline structure of the films. The morphological study indicates the formation of a uniform particle such as granular and nano-flower structures on the surface of the films. The most important morphological change was observed at 3% indium doped thin film, which has nano-flower surface morphology. The gas sensing measurements were performed for different temperature and different NO gas concentrations. The maximum gas sensitivity was revealed at an optimal indium doping concentration of 3 at.% that achieved the highest sensitivity with a value of 22.4 for 50 ppm NO gas at 167 degrees C.