Poly{sodium 2-[omega-methacryloyl oligo(oxyethylene)] ethylsulfonate}s were synthesized as a single-Na+-ion conductor. Salt content, glass transition temperature (T-g) and the length of oligo(oxyethylene) side-chain in the polyelectrolytes highly influence isothermal conductivity, among which the T-g has proven to have much effect on the conductivity. The highest conductivity of 3.5 X 10(-6) S/cm at 25 degrees C was obtained for the polyelectrolyte with the number of oxyethylene units of 14, which has a lowest T-g of -43 degrees C. Isothermal transient ionic current technique was used to evaluate the mobility of carrier ions. The conductivity, mobility and the number of carrier ions were studied as a function of the ambient temperatures, and the results reveal curved Arrhenius plots. The number of carrier ions was found to increase with the elevated temperature. Thus, it might be reasoned that the temperature affects ionic conductivity of the polyelectrolytes by means of changing segmental motion and the number of carrier ions.