In order to delay the onset of corrosion structures subjected to atmospheric degradation, such as aircraft, exterior metal surfaces are frequently covered in a corrosion prevention organic coating system. Organic coating systems, in many cases, provide a reservoir of corrosion inhibitors along with establishing a critical electrolyte barrier between the atmosphere and the structure. These coating systems include a surface pretreatment, a primer barrier layer that can contain a sacrificial inhibitor additive, and a topcoat that also provides corrosion barrier properties and other additives for color. Improving our understanding, and modeling how these coating properties change, as a function of exposure to a variety of service environments can decrease maintenance costs associated with paint removal, and re-painting. A model that can incorporate the fundamental effects of various environmental parameters can provide damage predictions based upon the measured environmental data.To that end, the initial phase of this program has focused on testing and monitoring a US Navy aircraft coating system, exposed to a variety of degradation conditions that simulate the extreme ranges of environmental stresses expected to be seen in-service. Coating condition was monitored using electrochemical impedance spectroscopy (EIS) and characterized using equivalent-circuit models so that changes to the coating system properties could be quantified and tracked over time.