Co-MgF2 granular films were deposited in thermionic vacuum arc plasma with simultaneous ignition of plasma in Co and MgF2 vapours. The samples were investigated by transmission electron microscopy which revealed Co grains of a few nm in diameter embedded in the MgF2 matrix. The crystalline phase for Co and MgF2 was studied by electron diffraction after selecting a typical area of the sample. Low-angle x-ray diffraction method was used to verify the bulk crystalline structure of the samples. The surface morphologies of the films were investigated by atomic force microscopy. The magneto-optical longitudinal Kerr rotation spectra of the films were also measured and compared. (C) 2010 Elsevier B.V. All rights reserved.