The behavior of a PEM fuel cell working under severe dehydration conditions has been experimentally studied with a segmented cell. When dry feeding gases are used in both electrodes, a drying front forms and propagates through the membrane. The total area of the membrane appears divided in two differentiated zones: a part that remains fully hydrated and another one that becomes dehydrated, both zones being separated by a border (drying front) whose progress entails the spreading of the dry area and finally triggers the complete shut down of the cell. The inner structure of the drying front has been analyzed and its propagation is described by averaging through the front thickness the effects of the transport mechanism of water in the membrane. By matching the predictions of the cell voltage evolution with the experimental voltage drop, a unique function describing the evacuation of water from the cell has been found to fully characterize the collapse of the cell. Copyright (c) 2011, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.