A conventional polyolefin spacer netting used for electrodialysis was transformed into an ion-exchange spacer by chemical modification. The application of the reacted ion-exchange spacer in electrodialysis units reduced cell-pair electrical resistance and diminished problems that can arise as a result of uneven water distribution in the stack, such as water splitting, fouling, and scaling. The ion-exchange spacer thus facilitated the production of high-quality water by an electrodialysis process with a low energy requirement.