In the present paper, the ionic conducting properties of sulfonated poly(phenylene oxide) (PPO) and its alkali-metal salts were investigated in detail. It was found that the material had moderate conductivity, which could reach as high as 10(-6) S/cm at room temperature. Its conductivity dependence on temperature conformed to the Arrhenius equation in a temperature range of 20-90 degrees C. The cation’s transference number determined by polarizing reversion was approximately unity. Differential scanning calorimeter, X-ray diffraction, and transmission electron microscope were used to analyze the condensed state structure of the material.