Fluorine-containing gases (e.g., CF4, SF6, and XeF2) are utilized in various industrial processes. However, these gases are toxic and detection of their leakage is crucial for safety reasons. In this study, the detection mechanism of a fluorine-containing gas is provided by hydrogenated palladium loaded on titanium dioxide (Pd-TiO2) upon XeF2 gas exposure. The color of the Pd-TiO2 nanocomposite changed from light gray to dark gray after hydrogen annealing. When the Pd-TiO2 was exposed to XeF2 gas, the initial light gray color was restored. The reflectance of Pd-TiO2 increased from 15% to 30% after XeF2 treatment. Incorporation of H and F resulted in an increase in the intensity of Ti3+ signal in EPR and a change in the sub-gap electronic state, identified using UV-vis spectroscopy, with H-2 and XeF2 gas treatment of bulk TiO2. A physiochemical model and electronic band structure is suggested by based on these results as well as XPS results for the reaction and gasochromic mechanism. The results also indicate electrical response of Pd-TiO2 to F sensing at 100 of conductance ratio of sensing to standby condition, suggesting the possibility of bimodal gaseous F detection.