The charging of islands in discontinuous metal films, deposited onto an insulating substrate, was experimentally shown by the method of ultraviolet photoelectron spectroscopy (UPS). This phenomenon can be observed when islands are small and far apart, before the appearance of the percolation threshold. The photoelectric response of discontinuous metal films gives more detailed information about the film structure than that obtained from the direct measurements of the electric conductance. It seems that some characteristic points of the kinetics of thin film growth such as the beginning of formation of island aggregates or the appearance of the percolation threshold can be controlled by the measurements and analysis either of the UPS curves or of the integral photocurrent.