Lecoq de Boisbaudran came from a wealthy family of distillers from Cognac in southwestern France. Of independent means and excited by the new spectroscopy of Gustav Kirchhoff, he built his own laboratory. In 1859, using spectroscopic techniques, he began searching for new minerals and elements.

In 1874, while examining a sample of zinc ore from the Pyrenees, Lecoq de Boisbaudran noticed some new spectral lines and discovered a new element, which he named gallium after the old name of his country. On hearing of the new element in 1875 Dmitri Mendeleev claimed this to be his long-predicted eka-aluminum, thus providing the first dramatic confirmation of his periodic table.

Lecoq de Boisbaudran later discovered two more elements: samarium (1879) and dysprosium (1886).