In this study it has been found that the potential of a galvanic tungsten-water interaction product (GTWIP) is more negative than that of the commercial W or high-purity monocrystalline W potential. It was shown that the GTWIP potential is a linear function of pH, and is also pWO(4)(2-) sensitive. The pH-sensitivity of GTWIP was explained by a multiphase and multilayer model consisting of a W(3 +) reservoir, an electroactive WO2 + WO3.2H(2)O mixture, a WO(3.)2H(2)O + HxWO3.2H(2)O mixture and an ion-selective HxWO3.2H(2)O membrane.