Complexes of poly(ethylene oxide) and having the general formula, with have been prepared. These materials are ionic conductors and electronic insulators. The conductivity of is highest, and is comparable to that of above 80°C. DSC analysis and a study of the temperature dependence of their conductivity indicate that these compositions consist of two crystalline phases, corresponding to pure PEO and the salt‐rich complex, and coexisting elastomeric phases. Initial transport number measurements indicate that these materials principally conduct anions.