In this contribution, a review of the efforts to improve membranes for fuel cells will be presented. Several themes will be interwoven:

1. What we have measured over the years, the insight provided and what is missing in most studies of membranes.
2. A historical perspective on the time-sequential major membrane issues, including some resolution and some circumvention of these issues.
3.  Types of membranes used and their relative merits as applicable to specific requirements.
4. Our state of understanding of membrane processes.
5. The roles of experimental and computational studies of membranes.

This talk is dedicated to Russ Kunz who always engaged in discussions as a gentleman with appropriate skepticism and obvious enthusiasm.

Acknowledgements

We gratefully acknowledge the long support of this work by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy FCTO, DARPA and by the Office of Naval Research. We also thank 3M, DuPont and Dow for providing membranes.