In situ DC resistance measurements were performed on semicontinuous niobium and silver films,which were made on mica and fullerene substrates in an ultra-high-vacuum chamber.Right after the interruption of the deposition,we investigated the changes (relaxation) of the sample resistance on a time scale of about 10 minutes.Resistance increase was observed for Nb/mica and Ag/C60 systems,and decrease for Ag/mica system.The relaxation is sensitive to substrate temperature and film thickness.We suggest that the edge diffusion and mergence of islands due to thermomigration of the metal atoms are responsible for the resistance relaxation.The intensity and direction of the relaxation reflect the interfacial activity of the metal/substrate system.The heterogeneities on substrate may also play an important role during this process.The analysis is presented from the angle of atom-migration and of thermodynamic evolution.