Ionic conductivity &sgr; and mobility &mgr; in the amorphous network polymers from poly(propylene oxide) (PPO) containing lithium perchlorate (LiClO4) at the concentration of [LiClO4]/[PO unit]=0.042 and 0.076 were investigated by means of complex impedance and time‐of‐flight methods. The &sgr; values of the PPO–LiClO4complexes reached 10−5S cm−1at 70 °C. The temperature dependence of &sgr; deviated from a single Arrhenius behavior above a critical temperature (−1 °C and 11 °C) which approximately corresponded to the glass transition temperatureTg. The &mgr; values were relatively high and changed from 10−6to 10−5cm2 V−1 s−1in the temperature range of 40–100 °C. The Nernst–Einstein equation correlated &mgr; with the ionic diffusion coefficientD. The Williams–Landel–Ferry equation withC1&bartil;5 andC2&bartil;30–50 held with a temperature dependence ofDin the order of 10−8–10−7cm2 s−1. The change in the number of ionic carriersnwith temperature obeyed the Arrhenius equation with the activation energy of 0.26 and 0.34 eV. The degree of dissociation for LiClO4in the PPO networks was 1–6%, and the dissociation was facilitated in the low LiClO4concentration complex. The temperature dependence of &sgr; aboveTgwas interpreted quantitatively in terms ofnand &mgr;.