The polyaniline-titanium dioxide (PANi-TiO₂) nanocomposite was prepared from PANi, and TiO₂, which were synthesized by oxidative chemical polymerization and sol gel methods, respectively. Nanocomposites of PANi-TiO₂ were doped with Camphor Sulfonic Acid (CSA) with concentrations as high as 50 wt %. The composites obtained (PT CSA) were characterized by X-Ray Diffraction (XRD), Fourier Transform Infrared spectroscopy (FTIR), and Scanning Electron Microscopy (SEM). The CSA doped PANi-TiO₂ thin-film sensors were prepared by the sol gel spin coating technique. The sensitivity measurements were carried out for ammonia (NH₃), ethanol (C₂H₅-OH), methanol (CH₃-OH), nitrogen dioxide (NO₂) and hydrogen sulfide (H₂S) gases, and it was found that the sensor exhibited selectivity to NH₃. The effect of varying doping percentage on response to varying NH₃ concentration was also studied. The result showed increasing response of sensor when NH₃ concentration was changed from 20 to 100 ppm. It was also found that, the sensor exhibited smaller response time and larger response magnitude but at the cost of longer recovery time.