Investigation on solid state rechargeable magnesium batteries are considered important similar to lithium batteries. In view of negligible hazard and less reactivity of the magnesium, in comparison with lithium, studies on rechargeable magnesium batteries are expected to have a wide scope in future. In the present investigations, decoupled ion conduction of poly(vinyl alcohol) (PVA)-based Mg-conducting solid polymer electrolytes (SPEs) is essential component of the studies. In common SPEs, ion transport has mostly been associated with the segmental motion of the polymer, so significant conductivity is only observed above the glass transition temperature of the system. But the results of ac impedance spectroscopy, FT-IR, XRD and AFM indicated that prepared PVA-based Mg-conducting SPE shows ionic transport decoupled from polymer segmental motion and high ionic conductivity at room temperature.