A tetragonal spinel CuFe2O4 reduced in H-2 flow at 633 K shows a self-assembled microstructure that exhibits fine dispersion of copper nanoparticles within the porous Fe3O4 matrix and high catalytic performance. Sintering of copper particles was inhibited significantly even after H-2 reduction at 873 K when CuFe2O4 Was used as a precursor, while it readily occurred for CuO and physically mixed CuO + Fe2O3. The high thermal stability of copper nanoparticles from the CuFe2O4 after H-2 reduction is ascribed to the immiscible interaction between copper and iron (or iron oxides). The spinel CuFe2O4 can be regenerated after an intentional sintering treatment (e.g., in H-2 at 873 K) by calcinations in air at 1273 K where the activity and the morphology restored completely. We show that metallurgical knowledge is available to tailor microstructure for designing catalysts. (C) 2010 Elsevier B.V. All rights reserved.