Holmium's atomic number is 67, its atomic weight, 164.9303, and its chemical symbol, Ho. It is a relatively soft metal with a melting point of 1,461° C (2,661.8° F) and a boiling point of 2695° C (4,883° F).

Credit for the discovery of holmium is usually assigned to Per Teodor Cleve (1840-1905), a Swedish chemist who was a professor at the University of Uppsala. In 1879, Cleve discovered that the rare earth mineral erbia was not a pure substance, but a mixture of three oxides. In addition to the oxide called erbia itself, the mineral also contained the oxides of two other elements, holmia and thulia. Cleve selected the name holmium for one of the new elements in honor of his city of birth, Stockholm.

Holmium had actually been identified the previous year by two Swiss chemists, Marc Delafontaine (1837-1911) and Jacque-Louis Soret. Delafontaine and Soret observed a previously unreported set of spectral absorption bands that they attributed to a new "element X." They later accepted the name holmium for their "element X."

Although holmium has some rather unusual magnetic and electrical properties, few important uses have been found for it.