The Distributed European Infrastructure for Supercomputing Applications (DEISA) was a European Union supercomputer project. A consortium of eleven national supercomputing centres from seven European countries promoted pan-European research on European high-performance computing systems. By extending the European collaborative environment in the area of supercomputing, DEISA followed suggestions of the European Strategy Forum on Research Infrastructures. The DEISA project started as DEISA1 in 2002 developing and supporting a pan-European distributed high performance computing infrastructure. The initial project was funded by the European Commission in the sixth of the Framework Programmes for Research and Technological Development (FP6) from 2004 through 2008. The funding continued for the follow-up project DEISA2 in the Seventh Framework Programme (FP7) through 2011. The DEISA infrastructure coupled eleven national supercomputing centres with a dedicated (mostly 10 Gbit/s) network connection provided by GÉANT2 on the European level and the national research and education networks (NRENs). There were 11 principal partners and four associate partners. Principal partners were: Max Planck Gesellschaft, Germany Bavarian Academy of Sciences and Humanities, Germany Barcelona Supercomputing Center, Spain CINECA, Italy CSC, Scientific Computing Ltd, Finland European Centre for Medium-Range Weather Forecasts, United Kingdom Jülich Research Centre, Germany Institut du Développement et des Ressources en Informatique Scientifique (CNRS), France Stichting Academisch Rekencentrum Amsterdam, Netherlands Edinburgh Parallel Computing Centre, United Kingdom High Performance Computing Center Stuttgart (HLRS), University of Stuttgart, Germany Associate partners were: CEA, Computing Complex, Bruyères-le-Châtel, France JSCC, Joint Supercomputer Center of the Russian Academy of Sciences, Moscow Swiss National Supercomputing Centre (CSCS), Manno, Switzerland The Royal Institute of Technologies - Center for Parallel Computers, (KTH), Stockholm, Sweden In 2011 services were taken over by the Partnership for Advanced Computing in Europe.