- J. Gutenberg-University
- J. Heyrovský Institute of Physical Chemistry of the ASCR
- JAIST - Ishikawa - Japon
- JDSU Uniphase
- JEUMONT ELETRIC
- JEUMONTELECTRIC
- JRC Institute for Environment and Sustainability
- JRC Institute for Transuranium Elements [Karlsruhe]
- JUNIA
- Jack Baskin School of Engineering
- Jacobs Technology ESCG
- Jacobs University [Bremen]
- Jakarta Islamic State University
- Jakokoski Observatory, University of Helsinki
- James Watt School of Engineering [Univ Glasgow]
- Janssen Research & Development
- Japan Advanced Institute of Science and Technology
- Japan Aerospace Exploration Agency [Tokyo]
- Japan Aerospace Exploration Agency [Tsukuba]
- Japan Agency for Marine-Earth Science and Technology
- Japan Atomic Energy Agency
- Japan Meteorological Agency
- Jawaharlal Nehru University
- Jaypee University of Engineering and Technology
- Jaypee University of Information Technology
- Jeju National University (KOREA)
- Jena University Hospital [Jena]
- Jeremiah Horrocks Institute for Mathematics, Physics and Astronomy [Preston]
- Jet Propulsion Laboratory
- Jet Propulsion Laboratory, California Institute of Technology
- Jeumont Electric, Altawest
- Jeunes Équipes de l'Institut de Physique du Collège de France
- Jilin Agricultural University
- Jodrell Bank Centre for Astrophysics
- Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University
- Johannes Kepler Univ. Linz (Germany)
- Johannes Kepler University Linz [Linz]
- Johannes Kepler Universität Linz
- John P. Hussman Institute for Human Genomics
- Johns Hopkins University
- Johns Hopkins University Applied Physics Laboratory [Laurel, MD]
- Johns Hopkins University School of Medicine [Baltimore]
- Joint ALMA Observatory
- Joint ALMA Observatory, Santiago
- Joint ALMA Office
- Joint Astronomy Centre
- Joint Centre for Hydro-Meteorological Research, Met Office Hadley Centre
- Joint Institute for High Temperatures of the RAS
- Joint Institute for Laboratory Astrophysics
- Joint Institute for VLBI in Europe
- Joint Japanese-French Robotics Research Laboratory [Japon]
- Joseph Louis LAGRANGE
- Jozef Stefan Institute [Ljubljana]
- Julius-Maximilians-Universität Würzburg
- Justus-Liebig-Universität Gießen = Justus Liebig University
- Jülich Centre for Neutron Science
- Jülich Centre for Neutron Science (JCNS), Forschungszentrum Jülich GmbH at Heinz Maier-Leibnitz Zentrum (MLZ)
- Jülich Research Centre
- Jülich Supercomputing Centre