Electrochemical behavior of potassium ferrate(VI) (K2FeO4) coated with different content of 2,3-Naphthalocyanine (H2Nc) is investigated as a function of exposure time in electrolyte. Galvanostatic discharge curves indicate that the stability of K2FeO4 cathode is improved by coating a layer of H2Nc. In short exposing time of 3h, the capacity of coated K2FeO4 shows slight decrease with increase of H2Nc content. But in longer exposing time of more than 6h, the K2FeO4 cathode coated with more than 2% H2Nc shows better capacity. Open-circuit potential curves indicate that the stability of K2FeO4 increases with increasing H2Nc content. Electrochemical impedance spectroscopy (EIS) results reveal that H2Nc partially hinders the contact between K2FeO4 and the aqueous media, and enhances the ability of electron transfer in the electrode, which are responsible for the enhancement of K2FeO4 stability.