tThis research paper reports the deposition of nanostructured pure and Ni-doped ZnO thin films depositedat the substrate temperature of 523 K using simple and economical spray pyrolysis technique andsubsequently post annealed at 673 K in air atmosphere for 3 h. Ni-doping greatly affected the crystallo-graphic orientation, surface morphology, roughness and room temperature sensing response. Noticeablechange in the crystallite size, transmittance and electrical properties was observed. The room tempera-ture sensing characteristics like selectivity, response recovery studies, range of detection, stability andreproducibility of the undoped and Ni-doped ZnO thin films were investigated. Especially, the sensingelements exhibited an excellent selectivity towards ammonia. A lower detection limit of 5 and 25 ppmwas observed for undoped and Ni-doped ZnO thin films respectively. The upper detection range waswidened to 1000 ppm for the Ni-doped film.