ODS steels are candidate materials for the future generation of nuclear power plants. Ferritic / Martensitic (F/M) ODS steels display better formability thanks to high temperature austenitic transformation. The precipitation kinetics of a F/M Fe‑9Cr ODS steel during powder consolidation up to 1100 °C has been characterized by in‑situ Small Angle X-ray Scattering (SAXS). The influence of the matrix phase transformation has been established, showing an increase of the growth rate of the nano‑oxides in austenite, leading to nano‑oxides ∼ 2x larger in diameter than in Fe‑14Cr ferritic ODS grades at the end of the thermal treatment. These results are further supported by local atom probe tomography (APT) performed across grains showing contrasted microstructure and composition. Anomalous SAXS as well as comparison between APT and SAXS provide evidence that the nano‑oxides stabilize with a Y2Ti2O7 or Y2TiO5 stoichiometry around 1100 °C.