The irradiation processing obtained from ionizing radiation sources is a nuclear technique widely used both in academic research and in industrial area, as for instance : sterilization of objects; nuclear medicine including diagnostic imaging, radiation oncology and radiological protection; development of innovative electronic materials; harmful effects on solid materials and so on. As a French public industrial and commercial establishment, IRSN (Institut de Radioprotection et de Sûreté Nucléaire) contributes to public nuclear security and safety policies, as well as health, environmental and crisis management policies. So, in the frame of its missions, IRSN carries out research, analysis and expert work in the fields of nuclear safety and radioprotection. One key topic concerns more especially the ionizing radiations as used in industry and medicine or naturally present in the environment. Thus, IRSN owns several irradiation facilities to perform its basic and applied research and to enhance its expertise in this specific area. This communication presents an overview of the irradiation facilities available in IRSN as well as the linked skills and expertise, especially covering the fields of medicine, environment and industry. These experimental facilities are designed to address all kinds of ionizing radiations such as alpha, beta gamma, X-ray and nucleons (proton, neutron) and over very wide ranges of dose rate and energy. The samples that can be studied thanks to them can cover from micro to macro scales and for both inert and living matters. For instance, irradiations can be applied in one hand from the biological cell to the full organism (animal or plant) and on other hand from nanomaterial up to equipment as large as several cubic meters. Moreover, some of these facilities are also able to perform online measurements during the irradiation process. The main technical features of the irradiation facilities are detailed hereafter: type of radiation, dose rate, energy, irradiation conditions (temperature, pressure, type of atmosphere, etc.) and size of samples. The experimental sensors linked with the facilities allowing on-line measurements during the irradiation phase are also presented. Finally, the skills and expertise of IRSN are pointed out by showing some major outcomes coming from the R&D, Industry or nuclear fields. Through this communication, IRSN aims to promote its irradiation facilities and to share its skills and knowledge with both the national and international networks and with both the scientific and industrial communities having potential needs in irradiation processing.