The possibility of producing a biodegradable polymer electrolyte based on poly-e-caprolactone (PCL) with different concentrations of LiClO4 has been investigated. The maximum ionic conductivity obtained at room temperature was 1.2 x 10(-6) S cm(-1) for PCL complexed with 10 wt.% LiClO4. In this mixture, complete biodegradation occurred after 110 days and was attributed to the presence of ester groups in the polymer matrix. The large electrochemical stability window of approximately 5 V showed that the PCL/LiClO4 electrolyte had important electrochemical properties that would make it useful in the production of rechargeable batteries with a lower environmental impact. (c) 2005 Elsevier B.V. All rights reserved.