Gd 2 O 3 thin films were grown on Ge (001) substrates by molecular beam epitaxy. The epitaxial character of the film is demonstrated by electron diffraction during the growth. The structural characterization of the films shows that the Gd 2 O 3 forms a bixbyite polymorph with a (110) out-of-plane orientation. The formation of bixbyite structured Gd 2 O 3 is discussed in terms of the atomic arrangement of the oxide planes on the Ge (001) surface.