The invention provides a unitized membrane electrode assembly having a first gas diffusion backing having sealing edges; a polymer membrane; a second gas diffusion backing having sealing edges; a first electrocatalyst coating composition present at the interface of the first gas diffusion backing and the polymer membrane; a second electrocatalyst coating composition present at the interface of the second gas diffusion backing and the polymer membrane; and a thermoplastic polymer, fluid impermeable, seal, wherein the thermoplastic polymer is impregnated into the sealing edges of the first and second gas diffusion backings, and the seal envelops a peripheral region of both the first and second gas diffusion backings and the polymer membrane.