During the 1920's and 1930's several workers claimed to have found element 85 in natural sources. We know today, however, that all astatine isotopes are highly radioactive, and the amount of astatine present in nature is so small that these early reports must be erroneous.

The element was first characterized in 1940 by Corson, Mackenzie and Segré, who synthesized the isotope At 211 by bombarding bismuth with alpha particles. They observed chemical behavior somewhat similar to that of other halogens and named the new element "astatine", from the Greek "astatos", meaning "unstable".