[en] The adsorption stage of forming the Eu-Si(111) interface boundary within the wide temperature range was studied through the methods of thermal desorption spectroscopy, isothermal desorption spectroscopy, slow electron diffraction, electron Auger spectroscopy and contact difference of potentials. It is shown that ordering the adsorbed europium film within the whole interval of the coating degrees O < Θ ≤ 1.8 is accompanied by the silicon surface reconstruction. It is shown also that this self-consistent process is thermally activated. It is found that the europium ordered adsorbed layers consist of the 2D islands. the structure whereof depends on the quantity of metal, deposited on the surface. The energy of removing the atoms from the islands into the vacuum is determined. This energy decreases according to the reduction of the islands two-dimensional lattice. Such a character of its change is conditioned in the final analysis by the decrease in the number of the Si surface atoms, which are not directly bound with the Eu atoms