Single crystals of ice were grown from KCl solution and their dielectric properties were investigated as functions of concentration, frequency, and temperature. It was found that a limited amount of chlorine was incorporated into the crystal lattice of ice but no trace of potassium. The upper limit of the substitutional incorporation of chlorine was approximately 1 × 10−4M(g moles/1). The distribution coefficients of the solutes were obtained as functions of the KCl concentration of the mother solution.The static dielectric constant of the single crystals of ice decreased due to the chlorine incorporation and the activation energy of its dielectric relaxation was reduced to 5.8 kcal/mole. The low-frequency conductivity increased with the square root dependence upon the chlorine concentration, and its activation energy was 6.1 kcal/mole. The mechanism of the dielectric polarization and conduction was discussed in relation to the defects introduced by chlorine built in the crystal lattice.