We present our recent results on high temperature ductile amorphous oxide coatings and their key enabling role for heavy liquid metal fast reactors. Amorphous Al2O3 thin films, the progenitor of this new class of amorphous ceramics, exhibit an elastoplastic response under both tensile and compressive tests at room temperature (E. Frankberg et al. Science, 2019). A yield stress as high as 4 GPa (tensile and compressive) has been measured, with a plastic deformation as high as 7% in tension and 100% in compression. SEM in situ micromechanical tests suggest that this elastoplastic behaviour is maintained even for volumes of several microns cube. We extensively studied its behaviour under in-situ and ex-situ irradiation finding detectable damages only above 150 dpa (F. G. Ferré et al. Scientific Reports 2016). Nevertheless, above 650 °C a-Al2O3 crystallizes, losing its outstanding mechanical properties and switching to a brittle behaviour. This behaviour is accelerated by ion irradiation, with crystallization occurring as low as at 400 °C. This findings prompted us to develop a new formulation thermally stable up to 950 °C and up to 700 °C under irradiation. Besides these unique mechanical properties, the amorphous oxide coatings exhibit extreme stability under thermal stresses, near zero permeability to gases (H2 isotopes in particular) and inertness with respect to heavy liquid metal (Pb, PbBi, LiPb). For the above mentioned characteristics, these materials, as coatings on structural steels, are key enablers for next generation heavy liquid metal cooled nuclear fast reactors and for fusion power plants.