A membrane electrode assembly for a fuel cell and a fuel cell stack incorporating the same

A membrane electrode assembly for a fuel cell is disclosed. It comprises an electrolyte membrane, an anode facing one side of said electrolyte membrane and a cathode facing the other side of said electrolyte membrane. The anode and cathode each include a gas diffusion layer and the areal density of the gas diffusion layer of at least one of the anode or cathode varies in a direction across its surface. The invention also provides a fuel cell stack incorporating a plurality of membrane electrode assemblies according to the invention.