Alumina films have been successfully formed on austenitic stainless steels containing 4 and 5 wt % Al by selective oxidation of Al in a H2O/H-2 environment. gamma-alumina films have been formed by oxidation at 800 degrees C and delta-alumina films at 900 degrees C. Satisfactory corrosion resistance performance for ozone gas has been obtained for both gamma- and delta-alumina films. For ozonized water, delta-alumina films formed with pH(2)O/ph2 less than or equal to 1x10(-4) have good corrosion resistance while delta-alumina films formed with pH(2)O/pH(2)greater than or equal to 3 X 10(-4) or gamma-alumina films do not. Holes of a characteristic triangular shape are observed on the oxidized surface of stainless steels containing 4 wt % Al, probably caused by the habitual formation of precipitated beta-(Fe,Ni)Al. No such hole has been observed on the oxidized surface of stainless steels containing 5 wt% Al.