A fuel cell stack is disclosed having a number of stacked fuel cells, each having in series an anode-facing end plate, an anode, an ion-exchanging layer, a cathode and a cathode-facing end plate. The stack includes at least one conductive and flexible intermediate layer between elements of the stack. The intermediate layer is deformable implemented in terms of its thickness. The intermediate layer abuts and interacts, in a fluid-tight manner, with the end plates. The intermediate layer is further disposed between at least one of the anode-facing end plate and the cathode-facing end plate of adjacent fuel cells, an end plate of a stack and a cooling plate attached to said end plate and an end plate of the stack and a cathode-facing end plate.