Neutron measurements are conducted during heavy water electrolysis in a glass cell equipped with a palladium cathode and a platinum anode set in separate electrode compartments. The electrolysis shows neutron emission peaks at 5 h (runs 1 and 2) and at 20 h (run 3) after start-up. The neutron emission peaks were clearly detected by independent A and B 3He counter channels; the peak values exceed 3σ. The neutron emissions are confirmed to occur in bursts.