We report the results of ion irradiation influence on rare earth sesquioxides structure, which are materials of practical importance as a radiation resistant ceramics in nuclear applications. Y2O3, Gd2O3 and Er2O3 sesquioxides in the pellet form were irradiated by oxygen ions (O2+) beam with the energy of 30 keV and implantation fluence of 5 x 10(20) m (2). Samples are characterized by Grazing Incidence X-ray Diffraction (GIXRD), Raman spectroscopy and atomic force microscopy (AFM). By GIXRD it was found partial transformation from cubic (C) to monoclinic (B) phase only in Gd2O3, induced by O2+ irradiation. This was confirmed by Raman spectroscopy. Although full phase transition from C to B phase in Y2O3 was not observed, the splitting and broadening of the main intensity Raman band for C phase could be explained by the stress and the disorder induced by the quenching. Analysis done by AFM showed changes in surface topology, i.e. values of average roughness (Ra) and root mean squared roughness (RMS) were significantly changed after irradiation for all samples. RMSs in Y2O3 before and after irradiation were 35 nm and 26 nm, respectively. (C) 2009 Elsevier B.V. All rights reserved.