Composite membrane

The present invention relates to a composite membrane comprising at least one ion-conducting polymer and a network of randomly orientated individual fibres, wherein there is a continuous region of the membrane at one or both of the membrane faces wherein the density of fibres is lower than the density of fibres in the membrane as a whole. The invention further relates to processes for manufacturing membranes according to the invention, and membrane electrode assemblies comprising membranes according to the invention.