The aim of the present work was to study the effect of solution flow velocity and electric field strength applied to an electrodialysis with ultrafiltration membrane (EDUF) cell on chitosan oligomer electromigration kinetics and on chitosan oligomer mixture fractionation. It was shown that the effect of solution flow velocity was not significant, while the electric field strength showed a significant effect on each chitosan oligomer electromigration rate. The effect of the electric field strength was also significant on the separation possibility of the studied oligomers. It was shown that by using electric field strength of 2.5 V/cm, it was possible to obtain a solution composed only of the dimer and trimer until an operating time of 2 h. By increasing the electric field up to 5 and 10 V/cm, it was no more possible to separate the chitosan oligomers. Chitosan oligomer transport numbers were measured. It was found that they contribute to about 7% of total electric current carrying, while about 93% of the total electric current could be carried by the electrolytes. The system performance was also evaluated through electric field intensity measurement and membrane integrity evaluation. It was found that the membranes kept their integrity and no significant fouling was detected. EDUF appeared consequently as a very interesting and innovative technology for the separation at a large scale of oligosaccharide. (c) 2009 Elsevier B.V. All rights reserved.