Frequency response of tantalum rectifier having an oxidized film metamorphosed by heating treatment has been obtained experimentally. The smaller the area of the tantalum electrode which is in contact with electrolyte, the better frequency response is obtained. With the rise of the temperature of electrolyte, a gradual increase in output D.C. current is observed, but no temperature dependence of frequency response is observed in the temperature range of 5℃~90℃.