This work analyses the impact of the location of pinholes in polymer electrolyte fuel cells on the degradation of the electrodes. Defects with a diameter of 0.45 mm were created in a 25 cm(2) membrane electrode assembly (MEA) of a fuel cell. The MEA was operated and characterised using a segmented single cell. The effects of the pinholes on degradation were measured and evaluated. Defects affected the fuel cell behaviour during periods of hydrogen starvation, thus accelerating the degradation process of the carbon support as well as the loss of active platinum catalyst surface area. Furthermore, the effects of the induced pinholes on membrane degradation and performance decay were determined. Pinholes close to the anode inlet in general have shown a more severe effect on the fuel cell operation parameters, such as open circuit voltage, performance, membrane resistance and hydrogen crossover, than pinholes at any other locations. Also, electrode degradation was accelerated. These effects were mainly due to locally increased temperatures. (C) 2015 Elsevier B.V. All rights reserved.