  X-ray Absorption Spectroscopy (XAS) is a widely used X-ray diagnostic method.
While synchrotrons have large communities of XAS users, its use on X-Ray Free
Electron Lasers (XFEL) facilities has been rather limited. At a first glance,
the relatively narrow bandwidth and the highly fluctuating spectral structure
of XFEL sources seem to prevent high-quality XAS measurements without
accumulating over many shots. Here, we demonstrate for the first time the
collection of single-shot XAS spectra on an XFEL, with error bars of only a few
percent, over tens of eV. We show how this technique can be extended over wider
spectral ranges towards Extended X-ray Absorption Fine Structure (EXAFS)
measurements, by concatenating a few tens of single-shot measurements. Such
results open indisputable perspectives for future femtosecond time resolved XAS
studies, especially for transient processes that can be initiated at low
repetition rate.
