A simple method is proposed for the estn. of the current bypass from exptl. current potential (i-U) curves measured for a bipolar reactor and with a one element cell of similar geometry. The model is valid only in the region where a linear i-U relation was obtained. For the scale-up, a relation between the current bypass (y) and two dimensionless nos. (Gb and Bn) was derived. The y = Gb(Bn + 1) where Gb (Geometry no.) depends on the geometry and Bn (Bipolar no.) on the electrochem. parameters of the system. [on SciFinder (R)]