Abstract: The procedures and techniques of making silver-silver chloride elec-troprobes are presented in this paper. Starting from the first and second theorems of thermodynamics and combining the concept of the chemical potential, a relation equation between the chemical potential caused by differential concentration and the electrical potential measured by silver- silver chloride electroprobes is developed when there is a differential concentration in the salt solution. It is verified by experiments that the measured electrical potential is in good agreement with the theoretical value.