The synthesis of cobalt ferrites (Co x Fe 3-x O 4 ) materials with sympathetic size and tunable magnetic properties is used for the promising industrial and biomedical applications. Such cobalt ferrites nanoparticles have been employed by co-precipitation technique. XRD analysis revealed that the average crystallite size of synthesized powder is 9 nm using (311) peaks, and it has exhibited polycrystalline structure. FTIR spectroscopy showed the formation of ferrite phase with high-and low-frequency bands at 573 cm −1 and 455 cm −1 , respectively. The TEM images exposed that the materials have been well agglomerated along with spherical-shaped nanoparticles. EDX study confirmed the presence Co, O, Fe and C with stoichiometric composition and no more impurity detected in the spectrum. The VSM analysis revealed that the sample exhibits the hard magnetic materials. In addition, the magnetic anisotropy increases (19.05 → 344.84 erg/g) when Co is added with Fe 3 O 4 . EPR spectroscopy confirmed the ferromagnetic behavior of composites.