Magnesium-1,4-benzenedicarboxylic acid (Mg-TPA) and magnesium- 1,3,5-benzene tricarboxylic acid (Mg-TMA) MOFs were synthesized and successfully incorporated in a poly (ethylene oxide) (PEO) matrix as filler for different proportions of LiN(CF3SO2)2 (LiTFSI) as salt. The membranes prepared were thermally stable up to 360 ̊°C. The ionic conductivity of the polymer electrolytes was enhanced upon addition of MOF and a maximum conductivity of 7.02 × 10−4 S cm−1 was achieved for CPE containing 10 wt % of Mg-TPA as filler. The interfacial properties of the CPEs with lithium metal anode were analysed by compatibility, Fourier transform infrared (FT-IR) and XPS analyses. Li/NCPE/Li symmetric cells were assembled and the dendrite growth was also studied. The lithium transference numbers (t Li +) was measured as 0.58 and 0.52 for the CPE containing Mg-TPA and Mg-TMA, respectively which is appreciable for battery applications. The influence of different organic ligands on the electrochemical and interfacial properties of solid polymer electrolytes was investigated and discussed.