Polycrystalline MoS2 grown by Mo sulphurization was exposed to increasing doses of Ar+ ions at 250 eV starting from 2.2 x 10(15) ions/cm(2) to 3.92 x 10(17) ions/cm(2). Electronic structure changes were monitored by X-Ray Photoelectron Spectroscopy (XPS) and Inverse Photolectron Spectroscopy (IPES). No change in the Fermi level position was observed with Ar+ dosing. Ion bombardment resulted in a new visible feature at lower binding energy in the Mo3d core level, while the S2p lineshape showed little changes. The formation of a steady state from 2.49 x 10(17) ions/cm(2) has been detected. The investigation of the occupied and unoccupied states on the steady-state surface pointed to the simultaneous presence of metallic-like Mo with amorphous MoS2-X. (C) 2016 Elsevier B.V. All rights reserved.