Four vinyl monomers containing a covalently bonded cation ethylimidazolium and various anions — Br, (CF3SO2)2N, (CN)2N, and CF3SO3 have been synthesized. High-molecular-mass polymers (Mw up to 1.84×10(6)) having the structure of ionic liquids have been prepared via the free-radical polymerization of 1-vinyl-3-ethylimidazolium in bulk and molecular and ionic solvents. The thermal stability and heat resistance of the resulting polymer salts have been estimated. It has been demonstrated that the thermal characteristics of these salts significantly depend on the nature of anions. The glass-transition temperatures of the polymers range from 19 to 235°C. The ionic conductivity of the polymer salts and their compositions with individual ionic liquids has been studied in the frequency range 50–10(6) Hz. The highest conductivity (1.5×10(–5) S/cm) is exhibited by the polymer containing the (CN)2N anion.