X-ray absorption spectroscopy (XAS) is one the most commonly used synchrotron techniques to probe the local and electronic structure of materials under extreme conditions of pressure and temperature. Here, the devices commonly used to generate pressure and temperature in XAS experiments are described: the large-volume Paris–Edinburgh cell and the diamond anvil cell. The technical issues linked to the demands of XAS and the solutions used by, and modifications of, such devices are discussed. Finally, methods for dynamic compression are briefly described.