Ionic conductivity is one of the most important properties for electrolyte membrane. The hydroxyl conductivities of the OH form membranes were measured by a two-electrode AC impedance method in a homemade cell. The cell was connected to a Parstat 263 electrochemical equipment (Princeton Advanced Technology, USA). The membrane sample was sandwiched between the two stainless steel electrodes and the resistance through the plane was measured, as described in our previous works [13,16,20,21]. The impedance spectrum was recorded in the frequency range from 0.1 Hz to 100 KHz. All the membrane samples were soaked in deionized water for at least 48 h before the test. The ionic conductivity can be calculated as follow: