Au-MgF2 nanoparticle cermet films with An volume fraction of 6-50% were prepared by radio-frequency magnetron co-sputtering and analyzed by X-ray diffraction, X-ray photoelectron spectroscopy and temperature-varying four-wire technique. Microstructure analysis shows that the films are composed of mainly amorphous MgF2 matrix with embedded fcc Au nanoparticles with a mean size of 9.8-21.4 nm. The electrical properties of the films from 54 to 300 K were measured. The results show that the electrical percolation threshold occurs between An 40 vol.% and 50%, and around the percolation threshold the electrical conductivity of the films changes by four orders. (C) 2007 Elsevier B.V All rights reserved.