A monochromatic X-ray beam is directed at the sample. The photon energy of the X-rays is gradually increased such that it traverses one of the absorption edges of the elements contained within the sample. Below the absorption edge, the photons cannot excite the electrons of the relevant atomic level and thus absorption is low. However, when the photon energy is just sufficient to excite the electrons, then a large increase in absorption occurs known as the absorption edge. The resulting photoelectrons have a low kinetic energy and can be backscattered by the atoms surrounding the emitting atom. The probability of backscattering is dependent on the energy of the photoelectrons. The backscattering of the photoelectron affects whether the X-ray photon is absorbed in the first place. Hence, the probability of X-ray absorption will depend on the photon energy (as the photoelectron energy will depend on the photon energy). The net result is a series of oscillations on the high photon energy side of the absorption edge. These oscillations can be used to determine the atomic number, distance and coordination number of the atoms surrounding the element whose absorption edge is being examined. The necessity to sweep the photon energy implies the use of synchrotron radiation in EXAFS experiments.

By reflecting the X-rays from a surface at grazing incidence and detecting the resultant X-ray fluorescence with a Si(Li) detector (see EDX), a more surface sensitive signal can be obtained. This technique is known as REFLEXAFS.

EXAFS spectra can be acquired in just a few seconds using the Quick EXAFS (QEXAFS) method.

SEXAFS provides even greater surface sensitivity than REFLEXAFS. A related technique is NEXAFS.