The effect of the incorporation of several lithium salts on the electrical and mechanical properties of polyurethane rigid (PUR) foams was investigated. Different amounts of lithium chloride (LiCl), lithium perchlorate (LiClO4), and lithium trifluoromethanesulfonate (LiCF3SO3) were added to the polyuretanic precursor. The salts affected the cellular microstructures and consequently the mechanical properties of the composite. Composite foams containing an amount of LiCl greater than 2 wt% showed low-surface resistivity (similar to 10(6) Omega), whereas the LiClO4 and LiCF3SO3 composites showed, in all range of filler percentage analyzed, high-surface resistivity values (similar to 10(11) Omega). This behavior was related to the different interactions between PUR and lithium salts, as confirmed by FTIR/Attenuated Total Reflectance analysis. Only the LiCl was able to create a motion of the ions Li+ and Cl- along the polyurethanic chains, because LiCl was completely dissociated. On the contrary, LiClO4 and LiCF3SO3 that affected the macromolecular structure of the polymeric network did not permit the formation of polyurethanic channels, where the ions could move, thus creating a charge motion. POLYM. ENG. SCI., 51: 1137-1144, 2011. (C) 2011 Society of Plastics Engineers