<p>In the present study, In₂O₃:Ti (0,1,2,3,4 and 5 wt%) thin films were prepared by a nebulizer spray pyrolysis technique. Structural analysis performed using XRD diffraction analysis confirmed the formation of In₂O₃:Ti thin films exhibiting a cubic structure with no additional phases, confirming substitutional doping. The lattice constant and unit cell volume decreased with increasing dopant concentration due to the smaller size of the Ti(IV) ion compared with the In(III) ion. FESEM images confirm uniform distribution of fine particles with high surface roughness and porosity for In₂O₃:Ti (3%) thin film, aiding efficient receptor function. UV-Vis spectroscopic analysis revealed that the optical band gap was modulated by changes in dopant concentration, attributed to alterations in the Fermi level and electronic structure of the semiconductor induced by the dopant. The In₂O₃ : Ti (3%) thin film showed a band gap of 3.57 eV indicating a blue-shift which could be attributed to the Burstein-Moss effect. Photoluminescence studies revealed characteristic emission lines in the visible region signifying the presence of oxygen vacancies in the sample. Pristine In₂O₃ sensors showed a detection limit of 5 ppm for ammonia. In₂O₃ : Ti (3%) sensor demonstrated a gas response of 197 to 250 ppm ammonia gas concentration. The response and recovery times of 5 s and 15 s illustrate the quick response of the sensor to ammonia gas. Linear response to the target gas ammonia over the concentration range from 50 ppm to 250 ppm, selectivity to ammonia over other gases against which the sensor was tested, and linear response to the target gas in various relative humidity environments with good stability characteristics make In₂O₃ : Ti (3%) a good choice of material for ammonia gas sensor applications.</p> Graphical Abstract <p></p>