Abstract: The present invention concerns a bridge substance for an electrode for measuring electrochemical values, particularly for measurement of the ion activity of a sample. The bridge substance comprises a solid, electrically conducting, chemically inert material including a ceramic doped with salts, a glass doped with salts, or of a mixture thereof. The invention further concerns an electrode having such a bridge substance. The present bridge substance allows the measurement of electrochemical values in highly alkaline samples and of samples containing organic solvents. The electrode according to the invention is also suitable for miniaturization.