We present in this work the results of neutron measurements performed on electrolytic cells containing deuterated Pd cathodes, using a high efficiency thermal neutron detection system in combination with a procedure involving a non‐stationary current through the cell’s circuit.Experiments carried‐out at our laboratory over a long period revealed a low level neutron production correlated with the current pulses, giving rise to characteristic patterns which were strongly dependent on the previous charging history of the cathodes employed.Another set of measurements was performed with essentially the same experimental set‐up, but on board a submarine 50 m under the sea surface. A very low background level was attained under these conditions, thus yielding a much improved signal‐to‐noise ratio as compared to our ground laboratory situation. The counting rates observed in the underwater measurements on cells containing deuterated Pd cathodes are well separated from those obtained in test (H2O) runs.