A discharge operating in a 80-cm-long discharge tube with an inner diameter of 15 mm, filled with a 3 : 1 neon–argon mixture at a pressure of 1 Torr, was investigated experimentally. Square voltage pulses with a period of 1 s were supplied to one of the tube electrodes, the second electrode being ungrounded. The initial stage of breakdown—the primary breakdown between the high-voltage (active) electrode and the tube wall, accompanied by the propagation of the prebreakdown ionization wave—was the same as in the conventional scheme with a grounded low-voltage electrode. Since the discharge gap was not closed, the discharge was not ignited. An essentially new effect was observed after the end of the voltage pulse. After a certain time interval, voltage spikes of opposite polarity, the amplitude and shape of which were close to those observed during the primary breakdown, appeared in the voltage and current waveforms of the active electrode. Simultaneously, a radiation pulse from the region adjacent to the active electrode was observed and an ionization wave began to propagate toward the second electrode. This work is dedicated to investigating this effect (which was named “reverse breakdown”) and analyzing its mechanism. A conclusion is made on the similarity of this phenomenon to the processes occurring in atmospheric-pressure dielectric barrier discharges.