The spectra of complex dielectric constant were measured on a fresh cement paste with a water/cement ratio of 0.4 sandwiched between insulated electrodes in the frequency range 10 kHz-1 MHz and temperature range between 0 degrees C and - 30 degrees C. The bulk dielectric constant, 30-20, and conductivity, 6.14 x 10(-5)-0.65 x 10(-5), in the temperature range - 10 to - 28 degrees C were much lower than those at room temperature, owing to the great decrease of ionic mobility caused by freezing the cement paste. The activation energy of 0.31 eV for the ionic conduction in fresh cement paste was obtained from an Arrhenius plot of conductivity at subzero temperature.