The exchange bias effect was studied on antiferromagnetic-ferromagnetic UO2/permalloy (Ni80Fe20) thin films. Films with a fixed thickness of UO2 layer and variable thickness of the covering Ni80Fe20 layer have been grown by reactive sputter deposition. The X-ray diffraction study showed epitaxial growth of the UO2 layer on (100) CaF2 substrates and a polycrystalline permalloy layer on top of it. The samples exhibited perpendicular exchange bias with the maximum magnitude of 22 mT found in UO2/Ni80Fe20 with the thinnest permalloy of 177 angstrom. (C) 2015 Elsevier B.V. All rights reserved.