A laboratory experiment is described to determine the primary current distribution in parallel-plate electrochemical reactors. The electrolyte is simulated by conductive paper and the electrodes are segmented to measure the current distribution. Experiments are reported with the electrolyte confined to the interelectrode gap, where the current distribution is uniform, and the case of unconfined electrolyte is treated by raising some segments. Experimental data are compared with theoretical results, and a close agreement is achieved. This experiment enables the student to gain a useful knowledge of the primary current distribution in electrochemical reactors. (Contains 1 table and 5 figures.)