Vacuum-deposited copper phthalocyanine (CuPc) film was bombarded by a low-energy argon ion (Ar +) beam. The surface changes induced were studied in detail using X-ray photoelectron spectroscopy. It shows that even if the ion energy is as low as 100 eV, the surface of the CuPc film undergoes severe structural changes. Ring rupture was clearly observed after only several minutes of ion bombardment. In addition, the original Cu(II) in CuPc was found reduced to Cu(I) and present with the residues of the damaged ring. The formation of this thin Cu(I) containing layer could significantly affect the overall properties of the CuPc film as an organic functional layer.