Temperature-dependent transport properties of Ge nanocrystalline films (nanofilms) prepared by the cluster beam evaporation technique have been studied. The nanofilms of thicknesses about 20 nm , deposited on the substrates at room temperature, exhibit non-linear current–voltage characteristics in the low bias range with decreasing temperature. In order to understand the conduction via the grain boundaries between two adjacent Ge nanocrystals, the temperature-dependent conductivity of the nanofilms has also been investigated, which could be explained by Mott's variable range hopping mechanism between 100 and 300 K . Below 100 K , the conductivity is limited by ordinary tunneling of carriers giving rise to temperature-independent behavior.