Physical and functional attributes are reviewed for recently developed Nafion(R) products that satisfy emerging fuel cell requirements-including stronger, more durable membranes, and polymer dispersions of higher quality and consistency for catalyst inks and film formation. Size exclusion chromatography (SEC) analysis has confirmed that dispersion viscosity is related to an "apparent" molar mass, resulting from a molecular aggregate structure. Membranes produced with solution-casting and advanced extrusion technologies exhibit improved water management and mechanical durability features, respectively. Additionally, DuPont has shown that experimentally modified Nafion(R) polymer exhibits 56% reduction in fluoride ion generation, which is considered a measure of membrane lifetime. (C) 2004 Elsevier B.V. All rights reserved.