Magnesium-based rechargeable batteries might be an interesting future alternative to lithium-based batteries since magnesium compounds are highly abundant in the earth and are environmental friendly. In this work, we have prepared polymethylmethacrylate (PMMA) based gel polymer electrolyte (GPE) films containing two different magnesium salts, which is magnesium triflate, Mg(CF3SO3)2 and magnesium perchlorate, Mg(ClO4)2 using solution casting technique. The ionic conductivity of both gel polymer electrolyte systems was evaluated using a.c impedance spectroscopy. Results show that at room temperature, GPE-Mg(CF3SO3)2 system exhibits the highest conductivity value at 1.27×10−3 S cm−1 for the film containing 20wt.% of Mg(CF3SO3)2 salt, while the highest conductivity value for the GPE-Mg(ClO4)2 system is 3.13×10−3 S cm−1 for the film containing 15wt.% of Mg(ClO4)2 salt. The conductivity-temperature studies of both GPE systems follow the Arrhenius behavior. The activation energies for ionic conduction were determined to be in the range of 0.18–0.26eV. The transport numbers of magnesium ions in both GPE systems were evaluated using the combination of a.c impedance spectroscopy and d.c polarization techniques. The results obtained indicate that the charge carriers in the GPE films for both systems are predominantly due to ions.