Eureka (often abbreviated as E!, or Σ!) is an intergovernmental organisation for research and development funding and coordination. Eureka is an open platform for international cooperation in innovation. Organisations and companies applying through Eureka programmes can access funding and support from national and regional ministries or agencies for their international R&D projects.

As of June 2022^[update], Eureka consisted of 43 full members, including the European Union (represented by the European Commission) and four associated members (Argentina, Chile, South Africa, and Singapore). All 27 EU Member States are also members of Eureka. Eureka has full members from non-European countries such as Canada, South Korea, and Israel.

Eureka is not an EU research programme, but rather an intergovernmental organisation of national ministries or agencies, of which the EU is a member. Cooperation and synergy are sought between Eureka and the research activities of the EU proper, such as with the European Union's Horizon 2020 and the European Research Area.

Founded in 1985 by prominent European political figures, Eureka has grown to one of the longest running European organisations dedicated to the financing of joint European R&D projects.

Eureka was established with the "Paris Declaration" of 17 July 1985, and its principles are based on the later Hannover Declaration, subscribed by Ministers on 5 November 1985. The two main founders were former heads of states, François Mitterrand (France) and Helmut Kohl (Germany). Other important personalities involved were Hubert Curien, French ex-Minister of research and former chairman of the European Space Agency, and Jacques Attali, adviser to François Mitterrand.

Briefly, it is about assuring the technological independence of Europe in the key domains of the future; encouraging, wherever possible, co-operation between European businesses and researchers; mobilising the necessary financial resources; accompanying the efforts of our enterprises by creating the necessary environment and supporting the unification of our internal markets.

There are numerous obstacles. Once the initial idea of Eureka was formulated, we were able to foresee the difficulties to be faced. But we know that each time we come together — for example to address high-energy physics, research into nuclear fusion, the development of an integrated space programme or the construction of crucial scientific equipment — our successes encourage us in the idea that we can work together in R&D areas close to industrial markets, despite the problems arising from the normal and legitimate competition between firms. François Mitterrand, Paris, 17 July 1985.

Before 1989, Eureka chairmanship changed hands every six months. Since then, the chairmanship rotates every 1 July, for a period of one year.