Preparation of polymeric nano-composites with finely controlled structure, especially, at nano-scale, is still one of the most perspective modification ways of the properties of polymeric composites. Paper actuality is based on growing need for non-combustible and safe battery electrolytes, which operate portable electronic devices [1]. Polyethylene oxide (PEO) solid composite electrolytes containing lithium triflate (LiTrifl), multiwall carbon nanotubes (MWCNT) and graphene (GR) by solution casting and hot-pressing method were prepared. Surface and volume resistivity measurements were performed to evaluate nanoparticles and lithium salt influence on the electric characteristics of the electrolyte material. Thermal stability of the samples ware investigated by differential scanning calorimetry (DSC). Observed enhancement of conductivity is connected to the addition of the Li+ ions and incorporation of the electrically conductive nanoparticles to the polymer electrolyte. It is observed an increase in the degree of crystallinity and electrical conductivity in MWCNT and GR induced PEO electrolyte.