The invention relates to a fluid conductivity measuring cell having two cylindrical and coaxial electrodes mounted head-to-tail and axially overlapping on the same insulative body, the inner electrode, penetrating partly into the at least partly hollow outer electrode has a recess in which the two electrodes are accommodated to form two cylindrical spaces, one of which is an external space formed between the internal wall of the recess and the external wall of the outer electrode and the other being an internal space formed between the external wall of the inner electrode and the internal wall of the outer electrode, the external space establishing communication between a fluid inlet and a fluid outlet of the cell, each discharging into the recess and being in fluid communication with the internal space that is surrounds, this internal space serving as a conductivity measuring area.