A process is provided whereby a membrane/electrode assembly for polymer electrolyte fuel cells whereby a high output voltage is obtainable within a wide range of current densities.A process for producing a membrane/electrode assembly 1 comprising a first electrode 10 having a first catalyst layer 12 and a first gas diffusion layer 14, a second electrode 20 having a second catalyst layer 22 and a second gas diffusion layer 24, and an electrolyte membrane 30, wherein the first gas diffusion layer 14, a first intermediate having the first catalyst layer 12 formed on the surface of the electrolyte membrane 30 by coating followed by annealing, and a second intermediate having the second catalyst layer 22 formed on the surface of the second gas diffusion layer 24 by coating, are bonded, so that the first catalyst layer 12 is located between the first gas diffusion layer 14 and the electrolyte membrane 30, and the second catalyst layer 22 is located between the second gas diffusion layer 24 and the electrolyte membrane 30.