This fuel cell is a test version of the electric-power generating device used on the two-astronaut Gemini spacecraft during seven missions in 1965-66. It was run for over 1000 hours to demonstrate long-duration functioning. A fuel cell is like a battery, in that it uses a chemical reaction to create an electrical current. Unlike a battery, a fuel cell will continue to generate a current as long as the reactants are supplied. The Gemini fuel cell used liquid oxygen and liquid hydrogen to generate electricity, with water as a byproduct. Oxygen and hydrogen molecules reacted and combined across a "proton exchange membrane," a thin permeable polymer sheet coated with a platinum catalyst.
The Gemini program pioneered the use of fuel cells in space, and a similar technology was subsequently used in the Apollo and Space Shuttle programs. General Electric, the manufacturer, gave this artifact to the Smithsonian.