Nanocomposite polymer electrolyte membranes were prepared by phase inversion technique in polyvinylidenefluoride–hexafluoropropylene (PVdF–HFP) matrix. These membranes were gelled with 0.5 M LiBOB in EC:DEC (1:1 v/v). These gel polymer membranes (GPMs) were incorporated with nanoparticles of AlO(OH) n and prepared composite polymer membranes (CPMs) also. The a.c. impedance analysis shows that AlO(OH) n filled membrane exhibits conductivity of 1.82 × 10 −3 S cm −1 at ambient temperature. The Li/CPM/LiFePO 4 cell delivered a specific discharge capacity of 158 and 147 mAh g −1 at first and at 20th cycle respectively discharged at C/20 rate. The cell experiences a capacity fade of 0.1 mAh g −1 cycle −1 over the investigated 20 cycles. The studies vindicate that AlO(OH) n filled PVdF–HFP polymer membranes could be the potential material to use as separator cum electrolyte in lithium batteries in conjunction with LiFePO 4 as a counterpart.