X‐ray photoelectron spectroscopy (XPS) was used to investigate the band alignment of lutetium oxide films with a germanium substrate. Lu2O3 films were grown on Ge (100) by atomic layer deposition. The conduction ‐ (CBO) and valence ‐ (VBO) band offsets of the Lu2O3/Ge heterojunction were determined to be 2.2 ± 0.1 and 2.9 ± 0.1 eV respectively. Internal photoemission measurements performed on metal‐oxide‐semiconductor devices gave a CBO of 2.1 ± 0.1 eV and a VBO of 3.0 eV, in excellent agreement, within the experimental error, with the values obtained by XPS. Copyright © 2006 John Wiley & Sons, Ltd.