An apparatus and method for measuring and monitoring the corrosion potential of engineering alloys used in aqueous systems is disclosed and claimed. The method is applicable for a variety of alloys including, but not limited to, copper-based, iron-based, nickel-based, other metallic-based alloys, and their combinations. The corrosion potential is typically determined by measuring a voltage between a specific material in the described oxidation-reduction potential measuring device and a reference electrode. Corrosion potentials for specific materials of construction may be used for diagnostic or control purposes.