The coating monitoring system is based on electrochemical impedance spectroscopy (EIS). The system consists of one or more compact and rugged mini-potentiostat modules coupled to one or more electrodes mounted on top of the paint coating of the structure being monitored. The electrodes and modules can be coated with a topcoat if desired. Alternatively, they may be mounted only temporarily to the structure for spot inspection. They periodically report to a laptop. Communications may be implemented using a wireless protocol. The units may be battery powered with an estimated battery lifetime of up to ten years, depending on the frequency of measurement and interrogation Alternative power supplies may be used to replace or supplement the battery to allow extended battery lifetime. Moisture, humidity, or other sensors may be incorporated into the coating monitor.