The discovery of gadolinium is generally credited to the Swiss chemist Marignac, who isolated the element from Mosander's yttria in 1880. It was independently discovered in 1885 by Boisbaudran who isolated the from Mosander's "didymia", a mixture of rare earths from which the cerium and lanthanum had been extracted. It was named in honor of the Swedish chemist Gadolin.

Elemental gadolinium is a metal resembling steel. It is active chemically as evidenced by its reaction with dilute acids to give the corresponding nitrates, chlorides, etc.