The exchange current densities of the Li+/Li couple reaction in polyether based electrolytes, 0.5 M LiCF3- SO3/poly(ethylene glycol) dimethyl ether whose molecular weight is 500 (PEGDME500), were investigated for the studies about charge-transfer reaction rate at the electrode/electrolyte interfaces. It was found that the exchange current densities in the PEGDME500 based electrolytes decreased with increasing amounts of PEGDME1000 (molecular weight: 1000). Raman spectroscopic studies indicated that the activity of lithium ions, which is a factor for the exchange current densities, was found to be the almost constant even with the addition of PEGDME1000 in to the electrolytes. The Gibbs activation energies for the interfacial reaction were also the almost constant. Meanwhile, inversely proportional relationships between the exchange current densities and viscosities of the electrolytes were observed. Our studies elucidated that viscosity of the electrolytes was the only important factor for the charge-transfer reaction rate at polyether based electrolyte/electrode interfaces.