The formation of thin organic films of copper phthalocyanine (CuPc) deposited onto the surface of gold-coated quartz crystal resonator was studied in situ under ultrahigh vacuum conditions by means of total electron-beam-induced current spectroscopy in combination with deposit thickness determination by piezocrystal microbalance technique. Variations in the fine structure of the total current spectra of CuPc layers of various thicknesses in the 0-8 nm interval have been analyzed and the electron mean free path in thin CuPc films was determined as a function of the electron energy. For electron energies of 5.0, 7.2, 14.4, and 18.0 eV above the Fermi level, the mean free path is 6.4, 3.9, 2.6, and 2.3 nm. (C) 2003 MAIK "Nauka / Interperiodica".