The high salt concentration of soybean oligosaccharides extract from sweet slurry, a byproduct of soybean sheet production limits its full utilization in the food industry. Conventional electrodialysis (ED) demineralization of the extract was performed to reduce the ion content. The effects of operation parameters on efficiency of desalination and oligosaccharides retention in the sweet slurry extract were investigated. The experimental results showed that high desalination efficiency and oligosaccharides retention could be achieved under optimal conditions of 20 V working voltage with 60 l/h flow rate, which resulted in a reduction of the total ion concentration from 5.022 mg/ml to about 0.26 mg/ml (94% reduction), and more than 80% of oligosaccharides retention in the dilute compartment. The result showed that ion-exchange membrane mediated electrodialysis was feasible for desalination of oligosaccharides extract from the sweet slurry. (C) 2009 Elsevier Ltd. All rights reserved.