process for preparing a solid , polymeric electrolyte , in membrane from , characterized in that : a mixture is prepared , which contains : a vinyl ether of formula r --. sub . n -- o -- ch ═ ch . sub . 2 wherein r = me or et and n is an integer comprised within the range of from 1 to 16 ; a divinyl ether of formula ch . sub . 2 ═ ch --. sub . m -- o -- ch ═ ch . sub . 2 wherein m is integer comprised within the range of from 1 to 10 , in a molar ratio to the vinyl ether comprised within the range of from 2 : 98 to 60 : 40 ; an ionic compound in an amount comprised within the range of from 1 to 30 % by weight ; an oligomer or a dipolar aprotic liquid in an amount comprised within the range of from 0 to 80 % by weight ; a photoinitiator in an amount comprised within the range of from 0 to 10 % by weight ; the above mixture is applied onto an inert support and is exposed to a source of ultraviolet light , or to an electron beam .