The general characteristics and spectrometric features of a high resolution four‐crystal reflection x‐ray monochromator with wavelength analysis installed at the HASYLAB beam lineLat DESY are presented. The monochromator is part of a spectrometer developed to calibrate x‐ray absorption edge spectra in the energy range of 6–36 keV with a relative uncertainty &Dgr;E/Efrom 10−5to 10−6. This requires an extremely effective suppression of harmonics and also a negligible instrumental influence in order to obtain almost intrinsic spectra. As the results show, the monochromator fulfills the requirements, including very high stability. An example of the calibration procedure for the copperKedge is given as well as a comparison of the remeasured absorption edge energies with the previously tabulated data. ©1996 American Institute of Physics.