This work focused on the evaluation of the oxide particles stability in neutron-irradiated ODS ferritic steels. Two types of ODS steels were examined and both had a single ferritic phase. The neutron irradiation was conducted in the experimental fast reactor JOYO. The initial microstructure in both steels had elongated grains along the axial direction and a dislocation structure with a high density produced during a mechanical alloying (MA) consolidation process. Oxide particles were distributed finely and uniformly over the ferritic matrix. The microstructure of irradiated ODS steels exhibited no void formation and a dislocation structure with high density. After irradiation, there were slight but significant changes in the size and density of the oxide particles. This change of the oxide indicated that recoil resolution of oxide particles might occur during neutron irradiation. Chemical analysis of the oxide particles by means of Energy Dispersive X-ray Spectroscopy (EDS) revealed that some of the oxide particles observed before and after irradiation had a complex configuration, such as a double-layered structure, implying that complex oxides with such a configuration are more stable than mono-oxides like TiO2 and Y2O3.