The sensitiveness and effectiveness of sensors in gas analyzers, which use tin dioxide and function on the principle of a near-surface area of spatial charge and changes of electric resistance of a film while adsorbing molecules of gases, largely depend on grain size and the presence of admixtures of noble metals. The research of the influence of admixtures on hydrogen, conducted in laboratory conditions, have established dependence of film surface resistance on the function of temperature and a mechanism of the given phenomenon.