Abstract
We study a pore scale model for the reactive layer of a fuel cell and derive effective equations. The cathode catalytic layer has a complex micro-structure to facilitate the transport of ion-gases and electrons. The reaction takes place at the surface of catalyst particles that are small compared to the pore space dimensions. The surface reaction law incorporates an exponential nonlinearity. The mathematical treatment is based on maximum principles and introduces a measure valued variant of compensated compactness.