An ion-selective electrode has a responsive glass membrane with an exterior thin film containing titanium dioxide of an anatase type that is continuously formed as an integrated body. The thin film, of several hundred nm in numbers, is electrically connected by an amount of titanium dioxide that will form a continuity in the thin film structure. The thin film can be porous and contain at least one metal selected from cobalt, nickel, tungsten, copper, platinum, gold, silver and iron. Additionally, significantly larger titanium dioxide particles of 0.02 μm in diameter can be further mixed into the thin film.