Solid polymer electrolyte (SPE) membranes with varying composition ratios were prepared from poly(vinyl alcohol) (PVA) and poly(acrylic acid) (PAA). The acrylic acid monomer with cross-linker was first blended with PVA polymer. A free radical polymerization was then carried out to form an alkaline polymer electrolyte. The solution casting method was used to form the solid polymer membranes. The solid polymer membranes were then immersed in 32 wt.% KOH solution to form different types of electrolyte, and the characteristic properties were examined with ac impedance, differential scanning calorimetry (DSC), stress-strain test, X-ray diffraction (XRD) and SEM morphology analysis. The results showed that the highest room temperature ionic conductivity for the PVA/PAA/KOH solid polymer membrane electrolyte system was 0.301 S cm(-1), which is a four-fold increase from that of the PVA-KOH electrolyte. These PVA/PAA composite polymer membranes also exhibited excellent thermal and mechanical properties. The membranes were stable for a wide temperature range. The PVA/PAA polymer membrane had good mechanical strength and ductility and would be a suitable polymer membrane electrolyte for the alkaline batteries and other electrochemical systems. (c) 2005 Elsevier B.V. All rights reserved.