AbstractNetwork polymer electrolytes based on poly[2‐(2‐methoxyethoxy)ethyl glycidyl ether] (PME2GE) were synthesized and characterized. The effects of crosslinking density, the introduction of ethylene oxide (EO) unit into the main chain by copolymerization, and the electrolyte (LiClO4) concentration on the ionic conductivity were explored. The random copolymer system improved the conductivity considerably compared with the polymer electrolytes previously obtained for network polymer systems and exhibited a high ionic conductivity of 10−4S/cm at 40°C and 10−5S/cm at 10°C, and even 3 X 10−7S/cm at −20°C with optimization of the copolymer composition, the crosslinking density and the amount of LiClO4. The optimum composition was EO/ME2GE = 70/30 in molar ratio. The most preferable ratio of LiClO4to etheric oxygen was in the rang