A highly deliquescent cationic polyether was synthesized through living anionic polymerization of epichlorohydrin followed by quaternization of the obtained poly(epichlorohydrin) by reacting with 1-methylimidazole. The formed poly(N-glycidyl-N'-methylimidazolium chloride) (poly(ECH-MeIm(+)Cl(-))) absorbed moisture in air immediately to change its appearance from solid to fluid, suggesting its deliquescent nature. The hydrated poly(ECH-MeIm(+)Cl(-)) possessed neither glass transition nor phase transition in between -60 and 60 degrees C. Ionic conductivity of the hydrated polymer was as high as 1.8 x 10(-2)S cm(-1) under rather humid conditions (23 degrees C, 80% RH; water uptake: 72 wt%).