Organic acids are increasingly used for various industrial applications. Their production is mainly achieved by fermentation. Precipitation or extraction stages, which generates big amount of effluents, are then traditionally used to get the acid in a suitable form. Bipolar membrane electrodialysis (EDBM) can be used to achieve the conversion of the acid salt into its acidic form. Its introduction in replacement of precipitation can significantly lower the environmental impact of the process. This paper is focused on the modelling of the conversion of weak organic acid salts by EDBM The different mass transfer phenomena involved in the system are first identified. A model is then established to get expressions providing the evolution of the product and effluent lines with respect to the operating conditions. The physical meaning of the characteristic parameters involved in the model is also discussed.