Abstract: Methods of deriving the cumulative maximum localized corrosion rate and cumulative localized corrosion rate factor for corrosion monitoring using coupled multielectrode array sensor probes are disclosed. Compared with maximum localized corrosion rate, which is derived from the corrosion rate on any of the electrodes of a probe that has the highest corrosion rate at a given moment of time, cumulative maximum localized corrosion rate is derived from the corrosion rate of the electrode that has been corroded the most in a given time period. The cumulative maximum localized corrosion rate is directly related to the corrosion damage (maximum localized corrosion depth); the maximum localized corrosion depth equals the integration of the cumulative maximum localized corrosion rate. Cumulative maximum localized corrosion rate should be used to evaluate the localized corrosion effect on metal damage.