The present review explored the different synthetic procedures of cobalt-based catalysts. Preparation methods of pure Co₃O₄, supported cobalt oxides and Co₃O₄-MO_x mixed systems were examined in details. In particular, precipitation and precipitation-oxidation methods for preparation of bare Co₃O₄, were investigated. Non-conventional techniques, such as spray pirolysis, atomic layer deposition, chemical vapour deposition, used in order to obtain films with tailored microstructure, were also contemplated. For supported cobalt catalysts and Co₃O₄-MO_x composite systems, the most frequently used preparation methods were co-precipitation and impregnation techniques. The effects of the nature of either, the support or the doping oxide, as well as of the cobalt precursor were studied. It was demonstrated that, among the various techniques, a surfactant-template method allowed to prepare Co₃O₄-MO_x systems highly homogeneous, with uniform mesoporous structure and high surface area. The effects on the morphological, structural, electronic, redox, acidic and basic properties were also considered. Examples of different characterization techniques, such as BET, XRD (X-ray diffraction), TEM (Transmission electron microscopy), SEM (Scanning electron microscopy), UV-vis spectroscopy (Ultraviolet-visible spectroscopy), TPR (Temperature programmed reduction), TPO (Temperature programmed oxidation), XPS (X-ray photoelectron spectroscopy), FT-IR (Fourier transform infrared spectroscopy), were given. Attention was paid to the catalytic application, with particular concern to CO, VOCs and CH₄ oxidation reactions. The use of cobalt-based systems as NO SCR catalysts was also reported.