Abstract: Some results of studying the unoccupied electron states and the formation of a boundary potential barrier during the thermal vacuum deposition of ultrathin 4-quaterphenyl oligophenyl films onto the surfaces of CdS and oxidized silicon were presented. Using X-ray photoelectron spectroscopy (XPS), the atomic Cd and S concentrations were established to be the same on the surface of a 75-nm CdS layer formed by atomic layer deposition (ALD). The electron characteristics of 4-quaterpheyn films with a thickness of up to 8 nm were studied in the process of their deposition onto the surface of a formed CdS layer and the surface of oxidized silicon by total current spectroscopy (TCS) within an energy range from 5 to 20 eV above E_F. The energy positions of major maxima in the fine structure of the total current spectra (FSTCS) of 4-quaterphenyl films were established. The positions of maxima were reproducible, when the two selected materials of substrates were used. A slight decrease in the work function from 4.2 to 4.1 eV during the thermal deposition of 4-quaterpheynl onto the CdS surface was established. The work function was revealed to grow from 4.2 to 4.5 eV, when a 4-quaterphenyl film was deposited onto the surface of oxidized silicon. Some possible mechanisms of physicochemical interaction between the 4-quaterphenyl film and the surfaces of the studied substrates that lead to different work function values observed on these substrates were discussed.