Cu/HfO2 nanocomposite powders were prepared by reactive milling under partial oxygen pressure as previously used to prepare Cu/ZrO2 nanocomposites. Cu/HfO2 nanocomposite powders with the same volumetric ceramic content were also prepared by direct milling of pure Cu with preformed HfO2 powder. Interestingly, in the case of preparation by treactive milling, the resulting HfO2 nanoparticles are amorphous. Direct milling of Cu and HfO2 powder did not result in any amorphisation of the latter. Full density compacts of the nanocomposite powders were prepared by hot uniaxial pressing under vacuum and by torsion straining at room temperature under a load of 5 GPa. The microhardness of the resulting compacts are reported.