PURPOSE: To stably decompose a fluorocarbon-containing gas oxidatively for long time by allowing the fluorocarbon-containing gas to contact with the catalyst consisting of the silicon carbide carrying plutinum at more than specified temp. under the atmosphere in which steam and air coexist.

CONSTITUTION: The fluorocarbon-containing gas is allowed to contact with the catalyst consisting of the silicon carbide carrying plutinum at ≥300°C under the atmosphere in which steam and air coexist. At that time, the fluorocarbon concn. in the fluorocarbon-containing gas is ≥0.1vol.% and the specific surface area of the silicon carbide is ≥1m2/g. In such a way, the fluorocarbon-containing gas is decomposed oxidatively for long time stably.