Nuclear magnetic resonance (NMR) spectroscopy and complex impedance spectroscopy have been used to study the polymer electrolytes formed by amylopectin rich starch, plasticized with glycerol and containing lithium perchlorate. The 7Li and 1H NMR linewidth narrowing occurs close to the glass transition temperature (T g ) of the plasticized electrolytes. The heteronuclear decoupling NMR experiments suggest a weaker Li–polymer interaction in the plasticized electrolyte when compared with the unplasticized ones. The effects of the plasticizer on the ionic mobility in these starch-based electrolytes, as measured by NMR spin-lattice relaxation and conductivity, are discussed. The 7Li NMR relaxation results indicate that the ionic mobility in these plasticized electrolytes seems to be controlled by the plasticizer molecules. The dynamical parameters obtained from the conductivity and NMR data demonstrate that the Li+ mobility in our systems is comparable to those found in others plasticized polymer electrolytes.