Polymer electrolyte membrane fuel cell performance degradation by coolant leakage and recovery

► Performance behavior by coolant leakage was studied in the PEMFC. ► Performance degradation showed only at anode of 3-cell stack after coolant injection. ► The performance of unit cell was easily reduced in short intervals and large dose of coolant injection. ► The reduced performance was recovered over 90% by water injection. ► The performance of exposed GDL was recovered by water cleaning, but the performance of exposed MEA was not.