Thomson-CSF was formed following the merger of two French companies, Thomson-Houston-Hotchkiss-Brandt and Compagnie Générale de Télégraphie Sans Fil. It was an electronics specialist on products such as broadcasting equipment, electroacoustics, shortwave radio sets, radar systems and television.

During the 1980s, the company embarked on a radical business restructuring due to its weak financial position. They started focusing on the European market rather than the Middle East and they created new divisions including Thomson Consumer Electronics. In 1982, they were nationalised, but in 1998, they were privatised again at which point they orientated themselves around defence electronics. They became keen to expand their defence and technology business and so, after a failed bid to merge with Marconi Electronic Systems, they successfully acquired Racal Electronics.

After this acquisition, the company conducted a strategic review of its businesses and adopted a new organisational structure that comprised of 3 businesses: defence, aerospace, and information technology and services. In December 2000, the company rebranded as Thales.