The process for producing perfluorocarbons according to the present invention is characterized in that in the production of a perfluorocarbon by contacting an organic compound with a fluorine gas, the organic compound is contacted with the fluorine gas at a temperature of from 200 to 500.degree. C. and the content of an oxygen gas within the reaction system is controlled to 2% by volume or less based on the gas components in the reaction starting material, whereby a perfluorocarbon reduced in the content of impurities is produced. According to the process for producing perfluorocarbons of the present invention, high-purity perfluorocarbons extremely suppressed in the production of impurities such as oxygen-containing compound can be obtained. The perfluorocarbons obtained by the production process of the present invention contain substantially no oxygen-containing compound and therefore, can be effectively used as an etching or cleaning gas for use in the process for producing a semiconductor device.