Powders and nanoceramics composed of composites of CoFe2O4, CoFe2, and a small amount of FeO were prepared by heating CoFe2O4 powder in reducing atmosphere and by sintering the product of reducing reaction at 350 degrees C via spark plasma sintering technology. In the powders, increase in the molar ratios of CoFe2:CoFe2O4 and a great change in magnetic parameters were observed with the change in heating temperature from 300 degrees C to 400 degrees C, and the dominance of dipole interaction over exchange coupling in the interparticle interactions was confirmed by the steps in magnetic hysteresis loops and the negative Henkel plots. However, in the nanoceramics, significant enhancement in exchange coupling was found when the sintering temperature was raised to 500 degrees C and 650 degrees C, which was confirmed by both the positivity of Henkel plot and the single-phase style of the magnetic hysteresis loop.