In December 1949, S.G. Thompson, A. Ghiorso and G.T. Seaborg carried out an ion-exchange separation of the products formed by the irradiation of milligram quantities of Am 241 with 35 MeV helium ions. A 4.5 - hour electron-capture activity eluting just ahead of curium was assigned to an isotope of a new element with atomic number 97 and mass number 243. The new element was named berkelium for the city of Berkeley, California, where it was discovered.
A visible amount of berkelium was isolated for the first time by Thompson and Cunningham at the University of California Radiation Laboratory in Berkeley in 1958. The first determination of the structure of a berkelium compound was carried out by Cunningham and J. C. Wallmann in 1962, using X-ray diffraction methods.
The metal can be made by reduction of BkF3 or BkF4 with calcium.