A fuel cell assembly with at least one PEM fuel cell for generating electrical energy from reactant gases includes at least one membrane/electrode having a membrane coated with platinum electrodes and, respectively positioned on each side, a porous gas diffusion layer, or having a membrane and, respectively positioned on each side, a porous gas diffusion layer coated with a platinum electrode, and also includes bipolar plates that lie against the gas diffusion layers and through which, during operation, a coolant flows, wherein at least one of the platinum electrodes has a smaller area than the gas diffusion layer, where the gas diffusion layer protrudes beyond the platinum electrode for a part of an edge region of the membrane/electrode unit, so that the formation of an electrochemical potential in this part of the edge region of the membrane/electrode unit is prevented in order to prevent damage to the membrane.