A series of mixed-substituent poly(organophosphazenes) with ethyleneoxy side groups has been synthesized. These polymers possess multiple electron-donor coordination sites that can form complexes with metal salts and generate "solid electrolyte" behavior. The polymers were characterized by P-31, H-1, and C-13 NMR spectroscopy, gel permeation chromatography (GPC), differential scanning calorimetry (DSC), and elemental analysis. All the mixed-substituent polymers have low glass transition temperatures, from -70 to -56 degrees C, as well as at least one melting transition. Several polymer-lithium triflate complexes were examined by impedance analysis. The maximum conductivities for these polymers ranged from 1.6 x 10(-6) to 3.9 x 10(-5) S cm(-1).