Two polymer electrolyte systems (unplasticized and plasticized) based on starch-chitosan blend doped with ammonium bromide (NH4Br) were prepared. The conductivity was found to be influenced by the number density (n) and mobility (mu) of the ions. The highest conducting plasticized electrolyte had n and mu values of 8.75 x 10(18) cm(-3) and 1.03 x 10(-3) cm(2) V-1 s(-1), respectively. Ionic transference number for the highest conducting plasticized electrolyte was found to be 0.92. An electrochemical double layer capacitor (EDLC) using the highest conducting plasticized electrolyte was cycled for 500times at 0.048mA cm(-2).