Many of steel oxidations concerned with the iso-thermal oxidation, and few reports on the non -isothermal oxidation have been published. Then the auther investigated the oxidation of non-isothermal type: from 500℃ to 1070℃by CO-CO₂-N₂ mixed gases which approximate the distribution of gases in the preheating zone of the coke and the coke-gas cupola. The results obtained are as follows: 1) The effect of carbon on the oxidation rate of steels is to increase slightly as increasing temperature. 2) The observed rate of oxidation using cubic specimen is a little greater than cylindrical or spheric specimen. 3) Weigh gain of oxidation at the center of coke cupola is a little less than that of wall, but the center of coke-gas cupola it is more increased than above. 4) The rate of non-isothermal oxidation can be expressed by the following equation. 수식 5) The Al₂O₃-bentonite coating mixture for the oxidation resistance is more efficient than the cement or the CaO-bentonite mixture.