Cobalt magnetic nanoparticles coated by carbon (Co/C) were synthesized by catalytic chemical vapor deposition (CCVD) with ethanol. X-ray diffraction, temperature programmed reduction, and magnetic measurements showed that in the CCVD process cobalt oxide (Co3O4) react with ethanol at temperatures between 700 and 900 degrees C producing magnetic metallic Co coated by different carbon materials such as graphite, and filaments. Thermogravimetric analyses suggest that the higher the temperature of CCVD process the higher the carbon content in the samples. Raman spectroscopy and transmission electron microscopy images show the presence of multiwalled carbon nanotubes encapsulating a cobalt metal core. The produced Co/C nanoparticles have been used as an adsorbent of organic compounds using methylene blue dye as a model molecule. The magnetic behavior of the materials indicated a high saturation magnetization at room temperature. This magnetic property can be useful for the separation of the adsorbent from the reaction mixture, which may be recovered after being used in the adsorption process. (C) 2013 Elsevier B.V. All rights reserved.