Cobalt oxide (Co₃O₄) nanoparticles were prepared using impregnation method associated with the liquid phase synthesis. Cobalt(II) nitrate hexahydrate (Co(NO₃)₂·6H₂O) was used as a starting material, and industrial pulp was used as impregnated matrix. As a result of heat treatment of cobalt oxide precursors impregnated with pulp for one hour at a temperature range of 380-800 ^oC, cobalt oxide nanoparticles with a particle size of 100-500 nm were obtained. The crystallization process, morphology, and thermal decomposition were studied as a function of firing temperatures. The synthesized powders were evaluated by Scanning Electron Microscope(SEM), X-ray diffractometer(XRD), Thermo gravimetric analysis(TG) and Differential scanning calorimetry(DSC). It is found that the formation of Co₃O₄ crystal phase is generated at about 380 ^oC. The crystal phase of Co₃O₄ is maintained to a temperature of about 800 ^oC, and the size of the crystals has increased as the temperature increases. This Co₃O₄ crystal phase was changed to a CoO crystal phase at 900 ^oC

Keywords: Nanoparticle, Cobalt oxide, Liquid phase synthesis