Abstract: A pH electrode having a pH-sensitive region on an electrically conductive support, said pH-sensitive region comprising a mixture of between 50% and 85% of the total mixture by weight of particles of a Group VA or Group VIII metal incorporated in, or applied to, a polymer substrate of a non-shrinking plastic selected from polyimides, the polymer substrate having a resistivity of 10 to 100 Kohms/square the metal particles including antimony particles and, when said particles are incorporated into said resistive polymer substrate, having said pH-sensitive region abraded to expose said particles.