Following procedures formerly developed for the prepn. of supported heterogeneous catalysts, carbon-coated cobalt nanoparticles dispersed on porous alumina have been prepd. by impregnation of γ-Al2O3 with (NH4)2[Co(EDTA)] and thermal decompn. in inert atm. Below 350 °C, Co(II) ions are complexed in a hexa-coordinated way by the EDTA ligand. The thermal treatment at 400-900 °C leads to the EDTA ligand decompn. and recovering of the support porosity, initially clogged by the impregnated salt. According to X-ray absorption spectroscopy, and due to in situ redox reactions between the org. ligand and Co(II), both oxidic and metallic cobalt phases are formed. Characterization by transmission electron microscopy, X-ray diffraction and magnetic measurements reveals that an increase in the treatment temp. leads to an increase of the degree of cobalt redn. as well as to a growth of the cobalt metal particles. As a consequence, the samples prepd. at 400-700 °C exhibit superparamagnetism and a satn. magnetization of 1.7-6.5 emu g-1 at room temp., while the sample prepd. at 900 °C has a weak coercivity (0.1 kOe) and a satn. magnetization of 12 emu g-1. Metal particles are homogeneously dispersed on the support and appear to be protected by carbon; its elimination by a heating in H2 at 400 °C is demonstrated to cause sintering of the metal particles. The route investigated here can be of interest for obtaining porous magnetic adsorbents or carriers with high magnetic moments and low coercivities, in which the magnetic nanoparticles are protected from chem. aggression and sintering by their coating. [on SciFinder(R)]