Abstract The ionic conductivities of some PECH-and PECH-PEO-alkaline salt complexes have been determined. The effect of some factors such as polar group concentration, cation size and anion size as well as procedure of thin film preparation on conductivity of polymer ionic conductor has been studied. For lithium salt complex the polar group reduces the conductivity, while for sodium salt complex the polar group enhances the conductivity. This phenomenon was explained by a model involving the existence of two kinds of potential well in the polymers. It has been found that the cation size has strong influence on conductivity. For both small Li+ and large K+ , the conductivity is low but for mediun size Na+, the conductivity is high. An ion transport picture in amorphous PECH has been proposed to illustrate this behaviour. In addition, it was shown that the larger the anion size is, the lower the conductivity will be. Finally, the re-sults suggested that the procedure of thin film preparation influenced the film conductivity.