The proposed article presents optimized Indium doped ZnO thin film for acetylene gas sensor. Thin films of ZnO and Indium doped ZnO of thickness 100 nm were successfully deposited on glass substrate using resistive thermal evaporation method. Structural properties have been performed by using XRD which reveals polycrystalline nature of the thin films. Morphological studies have been performed by using FESEM which reveals the information that thin film is homogeneous and uniform. AFM showed that with the increasing of indium doping concentration in ZnO resulting increment in vertical roughness of thin films. Further sample were tested for acetylene gas sensing using Keithley source meter and multimeter. The fabricated sensor (IZO-3) showed high sensitivity magnitude of 29.06 (100 ppm), short response and recovery time of 49.28 s and 58.45 s respectively at 150 °C operating temperature. IZO-3 sensor showed good linearity with good selectivity and excellent reproducibility. © 2020 Elsevier Ltd