The heat treatment of base-metal Ni electrode multilayer capacitors (MLCs) in air was investigated with a view to reducing manufacturing costs. This treatment was found to recover the insulation resistance in the same way as heat treatment under low oxygen partial pressure. At temperatures above 800°C, heat treatment in air was associated with cracking as a result of volumetric expansion of Ni through oxidation. TG-DTA analysis revealed that the oxidation behavior of Ni electrodes in MLCs differs from that of Ni plates or Ni fine powder. The capacitance of 1.2 μF MLCs in EIA 1206 size was successfully manufactured by the novel process.