The world's first highly durable PFSA membrane and MEA for PEMFC have been developed, which can operate for more than 6,000 hours at 120ºC and 50% relative humidity (RH). The MEA is comprised of a newly invented composite polymer (NPC polymer), which has exceptional chemical stability against degradation caused by the hydroxyl radical even at 120ºC. This achievement has opened up a new era of operating PEMFC in the temperature range of near freezing to120ºC under low humidity as well as under high humidity conditions for an extended period of time.