Interactions of silicon atoms on a Ru(001) surface have been studied by synchrotron radiation photoemission spectroscopy and low‐energy electron diffraction. A stable RuxSi1−xphase with high chemical uniformity was obtained by post‐annealing the sample at 1370 °C. Upon interaction with silicon, the Rudband was significantly narrowed (by about 1 eV), and shifted towards the Fermi level. The distributions of Si 3s,3pand Ru 4din the occupied valence bands were clearly identified by using different photon energies. The chemical nature of Si‐Ru interaction is discussed.