We report thermopower and electrical resistance of valence-unstable CeNi4Cu and its non-magnetic analogue LaNi4Cu in the range of temperatures between 4 and 900 K. Based on experimental data we analyze the contributions of cerium f-states to the total thermopower, considering electronic transport properties of the crystal matrix in which the f-electron subsystem is located. We demonstrate that CeNi4Cu is a concentrated Kondo system with high Kondo temperature, ТК, of approximately 1300 K, where temperature behavior of thermoelectric power manifests combined effects of Kondo scattering on localized f-centers together with scattering associated with the presence of a narrow d-band near the Fermi level. We further discuss the features of the temperature stability of the position of the narrow peak (so-called Kondo resonance) in the density of states at the Fermi level.