The existence is reported of a new class of polymer electrolytes, containing polyether backbones and pendent mesogenic groups. These are amorphous (and sometimes liquid crystalline) polymeric solids with sub-T-g conductivities approaching 10(-5) S cm(-1) at ambient temperatures. The apparent decoupling of ion transport from structural relaxations in the host material implies the existence of a truly "solid" polymer electrolyte, which also implies a link between ion-transport mechanisms in glasses and in polymeric materials. In future it should be possible to develop materials for a variety of electrochemical applications, based on this new design strategy.