Two case histories illustrate the use of simple electrochemical testing techniques for trouble-shooting corrosion problems in the chemical process industry. Simple electrochemical techniques that are within the capability of the non-electrochemical specialist are seen to be powerful tools for problem-solving. The measurement and interpretation of corrosion potentials, galvanic currents, and polarization curves, in particular, are presented. How these techniques are used by the production-support corrosion engineer and the researcher is seen to differ, because of their differing objectives and constraints. Accordingly, their work must be judged by different criteria.