Organophilic vermiculite was prepared by ionic exchange reaction between vermiculite and cetyltrimethylammonium bromide, and it was then used as filler to prepare a series of composite gel polymer electrolytes containing poly(methyl methacrylate) and room temperature ionic liquid 1-butyl-3-methylimidazolium hexafiuorophosphate. Surface morphology and structural nature of the composite electrolytes were examined by scanning electron microscopy and Fourier transform infrared spectroscopy, respectively. X-ray diffraction analysis confirmed that organophilic vermiculite decreased the crystallinity of polymer and formed intercalated polymer/layered silicate composite. On the other hand, the dispersion of organophilic vermiculite increased the thermal property of polymer electrolytes. Furthermore, the ionic conductivity and electrochemical window of composite gel polymer electrolyte reached up to the value of 4.01 x 10(-3) S cm(-1) and 3.8 V at the adding content of 8 wt.% organophilic vermiculite, respectively. (C) 2013 Elsevier Ltd. All rights reserved.