Electrochemical techniques including measurements of corrosion potential, redox potential, polarization resistance, electrochemical impedance, electrochemical noise, polarization curves, and electrochemical hydrogen permeation techniques have been applied to studies of microbiologically influenced corrosion (MIC). Applications include evaluation of MIC of metals exposed to seawater, fresh water, demineralized water, process chemicals, food stuffs, soils, aircraft fuels, human plasma, and sewage. In this review electrochemical data from laboratory and field applications are presented and interpreted in terms of mechanisms of MIC.