Plutonium was first isolated March 28, 1941 by radiochemist Glenn T. Seaborg and his team of scientists, working with the cyclotrons at the University of California, Berkeley.

The second transuranic element, and the most radioactive, it was named after the planet Pluto, but the discovery was not announced until after WWII.

Production of plutonium, which has a half-life of more than 20,000 years, started at the Argonne National Laboratories, IL.