As electrochemical techniques for corrosion research, monitoring, and control become more sophisticated, and improved software for the performance and analysis of electrochemical tests becomes available, more detailed information about corrosion behavior can be obtained from such tests. It is important, however, to consider the background and limitations of even such routine tests as polarization techniques. While improved instrumentation and the availability of commercial software have made it much easier to carry out electrochemical corrosion tests, it is important to plan the performance and analysis of such tests carefully. It is pointed out that neglecting the effects of the uncompensated resistance (“ohmic drop”) can cause severe distortions of polarization curves, underestimation of corrosion rates, and changes in the true scan rate of a potentiodynamic curve. Positive feedback and the interrupter technique can be used to eliminate such errors. The choice of the correct scan rate is an important factor in the performance of potentiodynamic tests. Electrochemical impedance spectroscopy (EIS) has broadened the range of corrosion phenomena which can be studied using electrochemical techniques. Examples of EIS applications include the evaluation of corrosion behaviors of polymer-coated metals and anodized Al alloys. EIS can be used as a quality control test for anodized Al surfaces and for chromate-conversion-coated Al alloys. It is pointed out that it is only possible to use the full power of the EIS technique if suitable models for the impedance behavior and fitting programs for the analysis of EIS data are developed. Examples for such models and software are given for polymer-coated steel and anodized Al. A model which describes the localized corrosion behaviors of Al alloys and Albased metal matrix composites is also presented.