In this paper, at first different corrosion mechanisms of bipolar plates (BPPs) in fuel cells and water electrolyzers are briefly reviewed. These corrosion mechanisms include corrosion of cathode and anode plates under active area conditions, shunt-current assisted corrosion, and possibility of galvanic and localized corrosion of bipolar plates. Then application of ex-situ corrosion test methods to study the corrosion behavior of bipolar plates are reviewed and their abilities and limitations with respect to in-situ operational conditions will be discussed in detail. Finally, application of the “Point Defect Model” to calculate the iron release rate under simulated operational conditions of bipolar plates of passive metals and alloys based to compare with ex-situ corrosion test results will be reviewed. This model can be used for estimating the formation rate of soluble and insoluble corrosion products that can cause acceleration of membrane chemical degradation as well as increasing contact resistance between the BPPs and Gas Diffusion Media (GDM), respectively.