A simple and rapid synthetic strategy for fabricating carboxy-functionalized iron oxide colloidal particles displaying reversible magnetic behavior is reported. The method is based on the pyrolysis of aerosols generated from ethanol/water solutions containing iron inorganic salts and mono- or polysaccharides. Essential to the success of the method are the use of hybrid (organo-inorganic) aerosols and the temperature of pyrolysis. The resulting material could be used in advanced biotechnological applications such as the magnetically assisted chemical separation of biocompounds.(c) 2006 Elsevier Inc. All rights reserved.