We report on an experiment conducted at the ESR storage ring aiming at the study of the X-ray emission of Xe 54 + ions colliding with Xe atoms at a beam energy of 50 MeV/u. The radiation resulting from the ion–atom interaction was observed using a high-resolution spectrometer based on metallic–magnetic calorimeter technology. In order to benchmark the capabilities of these detectors for high-precision atomic physics experiments, we identified several transitions from H-like and He-like xenon and determined their energies. Furthermore, the 1 s -Lamb shift in Xe 53 + was estimated using the measured line energies. The results are compared with previous experimental studies and theoretical predictions. Graphicalabstract