The construction of a scanning electrode system is described. The system is designed to measure chemical and electrical parameters above surfaces. It was tested with scanning reference and scanning pH electrodes on a steel coupon which contains a weld, several artificial corrosion pits of different depths and diameters, and an artificial crack of varying depth. The apparatus is computer controlled; the program for control of the apparatus is provided. A stationary electrode is utilized with a moved examined surface (a coupon). The apparatus is capable of determining surface dimensions of pits, but not pit depths. The artificial pits and crack were shown to be anodic locations. The solution above the pits and crack was more acidic than the solution above the remainder of the coupon.