After the liberalisation of Europe’s energy markets, Gaz de France also entered into the electricity sector, having developed combined natural gas-electricity offerings.

The company's capital was partially floated on the Paris Stock Exchange in July 2005, raising €2.5 billion for the State of France.

[7] On 25 February 2006 French Prime minister Dominique de Villepin announced the merger of Suez and GDF, which would make the world's largest liquefied natural gas company.

This plan for a merger between Gaz de France and Suez came under fire from the whole of the political left, which feared the loss of one of the last ways of preventing the price rises experienced over the previous three years, and by the social Gaullists and trade unions.

On 2 September 2007 the boards of directors of Gaz de France and Suez approved the new framework for the planned merger between the companies.

The newly created company, GDF Suez, came into existence on 22 July 2008; the world's second-largest utility and a group of €74 billion of revenues.