- X4C
- X4 Pharmaceuticals
- XD Productions
- XEGEN
- XEGEN, 15 rue de la République, 13420, Gémenos
- XEMA-MEDICA Co
- Xeno-canto foundation
- Xenocs SAS
- Xenon Pharmaceuticals
- Xenothera [Nantes, France]
- XenTech [Evry]
- XenTech [Évry]
- Xeolas Pharmaceuticals Ltd
- XeriusTracking SARL
- Xerox Company
- XGLab SRL
- XGLab S.R.L.- Bruker
- XGLab S.R.L – Bruker, Milan
- Xiamen University
- Xiangtan University
- Xiangtan University (XTU)
- Xi'an Institute of Optics and Precision Mechanics
- Xi’an Jiaotong-Liverpool University
- Xi'an Jiaotong-Liverpool University [Suzhou]
- Xi'an Jiaotong University
- Xi'an Shiyou University
- Xi'an University of Arts and Science (CHINA)
- Xi'an University of Technology
- Xichang College
- Xidian University
- Xinjiang Institute of Water Resources and Hydropower Research
- Xinjiang University
- Xinxiang Medical University
- XMOD Technologies
- Xploraytion [Berlin]
- Xploraytion GmbH
- X-ray Science Division
- XtreeE [Rungis, France]
- Xuanwu Hospital of Capital
- Xuzhou Medical University
- XWiki SAS [Paris, France]
- Xwing
- XXI Consulting