Protactinium was first identified by Kasimir Fajans and O.H. Göhring in 1913 while studying uranium's decay chain. The particular isotope they found, protactinium-234^m, has a half-life of about 1.17 minutes. They named the element brevium, meaning brief, and then continued with their studies. Protactinium's existence was confirmed in 1918 when another isotope, protactinium-231, was independently discovered and studied by two groups of scientists, Otto Hahn and Lise Meitner of Germany and Frederick Soddy and John Cranston of Great Britain. Protactinium was first isolated by Aristid V. Grosse in 1934.

Protactinium is a rare, poisonous and expensive element that is present in uranium ores in very small amounts. In 1961, the Great Britain Atomic Energy Authority was able to produce 125 grams of 99.9% pure protactinium, although they had to process about 55,000 kilograms of ore and spend about $500,000 to get it.

Protactinium's most stable isotope, protactinium-231, has a half-life of about 32,760 years. It decays into actinium-227 through alpha decay.

Due to its scarcity, high radioactivity and toxicity, there are currently no uses for protactinium outside of basic scientific research.