The durability and reliability of fuel cell products need to be improved. The lack of early diagnosis and failure-prevention techniques is one of the limiting factors. We present a non-invasive method for the early diagnosis of flooding, dehydration and low fuel stoichiometry (three common failure modes). Our method is based on microsensing electrodes (SE) that are placed at appropriate locations in a single cell. These electrodes have a characteristic potential response to each of the failure modes, which enables detection prior to overall fuel cell failure. The specific features in the measured responses (or combinations thereof) can be used to discern between different failure modes. and initiate corrective actions. (C) 2008 Elsevier B.V. All rights reserved.