A process for producing at least one of tetrafluorethylene and hexafluoropropylene by pyrolysis wherein perfluoroisobutylene is produced as a by-product and is reacted with an alkanol of the formula ROH, wherein R is an alkyl group of the formula C.sub.n H.sub.2n+1 and n is an integer from 1 to 6, to produce at least one ether compound selected from the group consisting of compounds of the formula (CF.sub.3).sub.2 CHCF.sub.2 OR and compounds having the formula (CF.sub.3).sub.2 C.dbd.CFOR, characterized by:
- reacting said at least one ether compound with water at an elevated temperature of at least about 75.degree. C. to produce at least one compound selected from the group consisting of 1,1,1,3,3,3-hexafluoropropane and 1,1,1,3,3-pentafluoropropene.