Nanosized semiconductor sensor materials with different palladium contents were obtained via zol-gel technology. Morphology and phase composition of nanosized sensor materials based on tin dioxide with palladium additives have been studied. Adsorption semiconductor sensors based on Pd/SnO2 nanomaterials were found to be highly sensitive to presence of CO and CH4 in air ambient. Higher responses to CO of Pd-containing sensors in comparison with their responses to CH4 were explained by higher reaction activity of CO in catalytic oxidation reaction. Differences in sensitive properties of the sensors to methane and carbon monoxide were explained by differences in catalytic activity of Pd/SnO2 nanomaterials in reactions of methane and carbon monoxide oxidation on surfaces of the gas sensitive layers of the sensors.