This paper reports on the electrical properties of various polymers (epoxy resin, silicone, polyurethane) filled with metal particles (Cobalt and Nickel). The results of this study give evidence of the expected non-conducting to conducting transition as the conducting filler volume fraction V-f is increased. The location of threshold is found to depend on the features and the properties of composite's constituents: the type, the viscosity and the surface tension of the matrix as well as the nature, the size, the shape, the geometry and the surface energy of the conducting particles and the composite porosity. The morphology of the filler particles and their dispersion in the matrix have been investigated by Optical and Scanning Electron Microscopies (SEM) and density measurements. The obtained results have been explained on the basis of the statistical percolation theory. (C) 2004 Kluwer Academic Publishers.