This paper is a review of electrochemical techniques as they were applied at the authors' research laboratories in investigations of corrosion phenomena associated with automotive cooling system metals in ethylene glycol solutions. Studies were conducted in the laboratory, in simulated service test assemblies, and in a moving vehicle. Investigations included the measurement of corrosion rates of cooling system metals during simulated and actual vehicle service; of component parts, such as a water pump and thermostat housing, during simulated service; of aluminum at heat-rejecting surfaces and in cavitating solutions; and of brass in inhibited solutions. The measuring and monitoring of corrosion rates was accomplished mostly by linear polarization (polarization resistance) methods. Other studies involved the use of either anodic polarization measurements or continuous current measurements at constant potential. Results show the applicability of electrochemical techniques to the study of practical automotive cooling system corrosion problems.