In the present work zinc oxide nanoparticles were synthesized using simple chemical method. The prepared nano zinc oxide was characterized using XRD and UV-Visible spectroscopy, S.E.M..T.E.M., The optical band gap was calculated from UV-Visible absorption measurement. The particles size was estimated using XRD pattern. Gas response of Zinc oxide films are checked for different concentration of reducing and oxidizing gases. The sensitivity measurement for selective ammonia gas with varying concentrations and stability studies have been carried out.