Nano ZnO filler incorporating gel co-polymer composites electrolytes membranes were prepared using a solution cast technique. All prepared membranes were characterized using different techniques such as X-ray diffraction (XRD), thermal analysis (TG, DSC), Fourier transform infra –red spectroscopy (FT-IR) and scanning electron microscopy (SEM). X-ray diffraction analysis showed the effect of lithium hexafluorophosphate (LiPF6), poly vinyl acetate (PVAc) and nano zinc oxide (ZnO) on the crystalline structure of the polyvinylidene fluoride –co– hexafluoro propylene (PVdF-co-HFP) matrix containing ethylene carbonate (EC) and diethyl carbonate (DEC) as plasticizers. FT-IR analysis confirmed the good dissolution of the LiPF6 salt and the good interaction of the nano ZnO filler with the co-polymer matrix. TG analysis showed the good thermal stability of the samples containing ZnO compared to the free one. Also, addition of nano ZnO filler enhanced the conductivity value of the co-polymer composites electrolytes. The sample containing 6 wt % of ZnO delivered the highest conductivity value of about 3.69 × 10−4 Ω−1 cm−1 at room temperature with a good thermal stability behavior (Td = 325 °C).