Patent ID: 8114552

Claim:
An electrode structure for a polymer electrolyte fuel cell comprising a pair of electrode catalyst layers containing carbon particles supporting platinum particles as a catalyst and a polymer electrolyte membrane sandwiched between the electrode catalyst layers, wherein said polymer electrolyte membrane is made of a sulfonated polyarylene-based polymer, wherein said sulfonated polyarylene-based polymer is a copolymer represented by formula (2): wherein m, l, and n are numbers; said sulfonated polyarylene-based polymer has an ion exchange capacity in the range of 1.7 to 2.3 meq/g; and said polymer contains a component insoluble in N-methylpyrrolidone in an amount of 70% or less relative to the total amount of the polymer, after said polymer is subjected to heat treatment for exposing the same under a constant temperature atmosphere of 120° C. for 200 hours.