A micro‐Raman study of polydioxolane (PDXL)/NaClO4and PDXL/LiClO4polymeric electrolytes has been carried out in a wide range of salt concentration, at room temperature. The ion–ion interactions and the precipitation of salt microcrystals in the host polymer have been evidenced by means of a line shape analysis of the band associated to the totally symmetric stretching mode (&ngr;1) of the ClO4−anion. The Raman spectra results reveal changes of the crystallinity of the PDXL/MCLO4systems which are directly related to the salt concentration. ©1995 American Institute of Physics.