Hyperbranched polymer was synthesized from pentaerythritol (as the central core), 1,2,4-trimellitic anhydride, and epichlorohydrin, and then hyperbranched polymer electrolytes with terminal ionic groups were prepared by the reaction of hyperbranched polymer with N-methyl imidazole. The chemical structure, thermal behavior, and ionic conductive property of the hyperbranched polymer electrolytes were investigated by H-1-NMR, FTIR, differential scanning calorimetry, thermogravimetric analyzer, and complex impedance analysis, respectively. The ionic conductivity of hyperbranched polymer electrolyte was up to 2.4 x 10(-4) S cm(-1) at 30 degrees C. (C) 2010 Wiley Periodicals, Inc. J Appl Polym Sci 117: 3539-3544, 2010