Pb&sngbnd;Al2O3&sngbnd;Pb structures have been fabricated by vacuum evaporation. For oxide thickness of approximately 300 Å, a forming process was noted. This forming process resulted in large electron transfer currents which were described as the sum of a temperature‐independent current plus a current with a voltage and temperature dependence appropriate to Schottky field emission into a solid. The forming process is assumed to be due to the establishment of a positive ion space charge which increases the field at the cathode.