The harmfulness sulfide in its free hydrogen of sulfide form is recognized to bring personal suffering at its lower concentration while at its higher concentration it may give a loss of awareness, permanent brain harmful or even death through asphyxiation. In this study after prepared and characterized chitosan, chitosan films have been prepared, and the cadmium ions were loaded on it to be used in the sensing of hydrogen sulfide gas electrochemically. The results showed that a remarkable variation in the electrical conductivity, in absence and presence illumination, with the time of the films under investigation in response to gas adsorption. Furthermore, the films were examined after the adsorption process of gas in many ways; resistor-capacitor circuit, thermo gravimetric analysis (TGA), FT-IR spectroscopic analyses, and scanning electron microscopy (SEM), were used to characterize the samples, and appear the differences before and after gas adsorption process.