In 1879 Elihu Thomson and Edwin Houston formed the Thomson-Houston Electric Company in the United States.
Early in 1892, Thomson-Houston and the Edison General Electric Company merged to form General Electric (GE) and also inthat year the company formed a French subsidiary, Thomson Houston International. In 1893 Compagnie Française Thomson-Houston (CFTH) was set up as a partner to GE.
In 1966 CFTH merged with Hotchkiss-Brandt to form Thomson-Houston-Hotchkiss-Brandt (soon renamed Thomson-Brandt). In 1968 the electronics business of Thomson-Brandt merged with Compagnie Générale de Télégraphie Sans Fil (CSF) to form Thomson-CSF. Thomson Brandt maintained a significant shareholding in this company.
In 1982 both Thomson-Brandt and Thomson-CSF were nationalized by François Mitterrand. Thomson-Brandt was renamed Thomson SA (Société Anonyme) and merged with Thomson-CSF.
From 1983 to 1987 a major reorganisation of Thomson-CSF was undertaken, with divestitures to refocus the group on its core activities (electronics and defence). Thomson-CSF Téléphone and the medical division were sold to Alcatel and GE respectively. The semiconductor businesses of Thomson-CSF were merged with Finmeccanica. Thomson acquired General Electric’s RCA and GE consumer electronics business in 1987.
In 1988 Thomson Consumer Electronics was formed, renamed Thomson Multimedia in 1995. The French government split the consumer electronics and defence businesses prior to privatisation in 1999, those companies being Thomson Multimedia (today Technicolor SA) and Thomson-CSF. The company changed its name to Thales from Thomson-CSF in December 2000.