Electrodialysis (ED) has been used as a membrane technique to concentrate tartaric acid from ion exchange regeneration waters obtained in grape juice treatment. The initial ion tartrate concentration in these streams varies between 1 and 10 kg m(-3) and can be concentrated more than 60% (53.2 kg m(-3) after 13 300 s). Permeate flux of ether common ionic components has been shown. Optimum intensities and current efficiency have been calculated with synthetic solutions. A mathematical approach has been used to predict final tartaric acid concentration and electro-osmotic effects.