Multilayers of the type Mo/a-Si:H and a-Si:H/Mo/a-Si:H were grown by magnetron sputtering ͑silicon and molybdenum͒ and plasma chemical vapor deposition ͑silicon͒, respectively. For a nominal Mo layer thickness between 0.1 and 34 nm, the temperature-dependent conductivity is investigated in the range between 10 and 300 K. The conductivity at 300 K of the films decreases from 5ϫ10 4 to 1ϫ10 Ϫ2 (⍀ cm) Ϫ1 with decreasing thickness. The thickness dependence of the conductivity is explained in terms of different mechanisms: grain boundary scattering for the thickest ͑nanocrystalline͒ films, surface scattering for the intermediate thickness ͑amorphous͒ films, and hopping between isolated Mo particles for the thinnest ͑discontinuous͒ films. For the interpretation of experimental data by scattering, an analytical solution of the Fuchs equation assuming pure diffusive scattering is presented. For Mo layers with 62% of bulk density, the conductivity of the nanocrystalline Mo layers is smaller than for amorphous Mo layers, which is related to the existence of free standing columns of the nanocrystalline Mo. The temperature-dependent conductivity of nanocrystalline layers with 93% of bulk density has a negative slope. For all amorphous films with a thickness of approximately 3 nm and for the nanocrystalline material with 62% of bulk density, the temperature-dependent conductivity is described by (T)ϰT 0.5 . With decreasing thickness, a gradual change from this law to a dependence according to (T)ϰexp͓Ϫ(T 0 /T)͔ n for the layers of minimum thickness is observed.