Carbon nanocapsules with iron core appeared to be a useful modifier of glassy carbon surface. It has been found that the presence of nanocapsules on the electrode surface resulted in a shift of the reduction voltammetric signal of oxygen by circa 250 mV toward less negative potentials. A considerable increase of the signal was observed when the modified electrode was exposed to an external magnetic field. The nanocapsules appeared to be a good substrate for immobilization of laccase. The presence of laccase on the electrode surface caused a further significant shift of the position of the oxygen reduction signal toward positive potentials. The application of external magnetic field again strongly magnified the current. The described phenomena were characterized in function of the magnetic field intensity and the angle between the electrode surface and the magnetic field direction. For explanation of the significant enhancement of O-2 reduction current the magnetic field profile in the vicinity of the electrode surface and the force of interactions of magnetic nanoparticles with paramagnetic oxygen molecules were calculated. (C) 2013 Elsevier Ltd. All rights reserved.