LaLuO3 films deposited on Ge were submitted to different postoxidation annealings. Electrical characterization revealed that such treatments can have beneficial effects on the characteristics of the dielectric layer. Nevertheless, LaLuO3/Ge interface characteristics are modified depending on annealing parameters and mostly on the employed atmosphere. Electrical characterization was correlated with physicochemical properties of the resulting structures, evidencing that oxygen annealing, in certain conditions, promotes substrate oxidation. A more stable interface without the formation of excessive Ge oxidized species was achieved using N-2.