A micro-porous composite polymer electrolyte (MCPE) was prepared in situ by adding TiO2 nanoparticles from the hydrolysis of titanium tetrabutoxide to a solution of poly(vinylidenefluoride-co-hexafluoropropylene) [P(VDF-HFP)] copolymer. The prepared microporous polymer films (MCPFs) were characterized by scanning electronic microscopy, X-ray diffraction, thermogravimetric analysis, FT-IR and electrochemical interface resistance. After the addition of TiO2 nanoparticles the polarity of CF2 groups in the polymer chains and the crystallinity of the MCPFs decreased. When the composite polymer film contained 8.5 wt% of TiO2 nanoparticles the MCPE exhibited excellent electrochemical properties such as high ionic conductivity, up to 2.40 x 10(-3) S cm(-1) at room temperature.