The oxidation behavior of SiCN-ZrO2 fibers and SiCN at 1350degreesC are compared. The as-measured parabolic rate constants for the two materials are nearly the same (15-20 x 10(-18) m(2)/s). However, after implementing a correction for the difference in the compositions, the rate constant is 13.2 x 10(-18) m(2)/s for the fiber, and 29.4 x 10(-18) m(2)/s for SiCN. The lower oxidation rate of the fiber is ascribed to the lower carbon content in the fiber material.