Two nanosized cupric oxide powders, which are synthesized by a vapor-phase reaction and aqueous precipitation, are surface modified with oleic acid to form cupric oleate on the surface. This enhances the dispersibility of cupric oxide powders in a nonpolar solvent of octane. The cupric oxide powder prepared by aqueous precipitation exhibits much better dispersion in octane than that synthesized by vapor-phase reaction. This is attributed to the presence of larger amounts of hydroxyl group on the particle surface, forming more cupric oleate and thus enhancing the colloidal stability of the resulting organic suspension.