Polymer electrolytes prepared with lithium perchlorate and low molecular weight poly(tetramethylene glycol) (PTMG) homopolymer and PTMG/poly(ethylene glycol) (PEG) copolymer were investigated. Complex impedance measurements, thermogravimetric analysis, differential scanning calorimetry and Raman spectroscopy were used to characterize the systems. Ionic conductivity results at room temperature for the homopolymer are lower than those reported for the well-studied PEG, while those for the copolymer are similar. The most concentrated samples showed the presence of crystalline polymer-salt complexes for both the polymer hosts. An increase of the ionic association with increase of salt concentration is observed,