Metallic films of palladium (Pd) and palladium-tin (Pd-Sn) have been deposited by evaporation technique. They were used as sensitive material for optical sensor by measuring the variation of absorbance. All samples were then oxidized by annealing at 500°C in low vacuum atmosphere. All the films were investigated by X-Ray Diffraction (XRD), Atomic Force Microscopy (AFM) to observe the influence of the structure and morphology on the optical properties of the films, carrying useful information for the sensing properties of the different sensing materials. Furthermore, the sensing performances were tested by monitoring the variation on the optical absorbance induced during the absorption / desorption of hydrogen gas. While the use of Pd for gas sensing has been widely covered for electrical and SPR sensors, this work aims to extend our comprehension of the optical sensing behavior, especially in absorbance-mode, of the thin films of PdO, Pd-Sn and PdO-SnO<sub>2</sub>.