| abstract |
To provide an electrolyte membrane for a polymer electrolyte fuel cell, capable of generating power in high energy efficiency, having high power generation performance regardless of the dew point of the feed gas and capable of generating stable power over a long period of time. A membrane used as an electrolyte membrane for a polymer electrolyte fuel cell, which comprises a cation exchange membrane made of a fluorinated polymer having cation exchange groups and having an ion exchange capacity of from 1.0 to 2.5 meq/g dry polymer, wherein some of the cation exchange groups are ion-exchanged with at least one type of ions selected from the group consisting of cerium ions and manganese ions. |