This paper reports results on the electrical properties of laminated epoxy composite containing 25 layers of carbon fibers in the form of mats. The dependence of the activation energy (calculated from DC resistivity measurements) on temperature reveals two independent conduction processes. The AC impedance is independent of the applied frequency below 75°C, and the real componet of the dielectric constant is also independent of temperature at high frequencies. The determined shielding effectiveness is dominated by the insertion loss. The observed optimum shielding effectiveness occurs at 30 mm spacing and applied frequency 9 GHz.