A process is disclosed for producing 1,1,1,3,3,3-hexafluoropropane and/or 1,1, 1,3,3-pentafluoropropene from (CF.sub.3).sub.2 CHCOOH and/or its water soluble salts. The process involves providing a mixture containing water and such carboxy compound(s) which has a pH of less than about 4, and reacting the mixture at a temperature of at least about 75.degree. C. Certain ether compounds may be included in the mixture along with (CF.sub.3).sub.2 CHCOOH and/or its water soluble salts. The reaction of the carboxy (and optionally ether) compound(s) with water may be employed in connection with a process for producing tetrafluoroethylene and/or hexafluoropropylene by pyrolysis, where by-product perfluoroisobutylene is reacted with water (and optionally an alkanol) to produce (CF.sub.3).sub.2 CHCOOH (and optionally one or more ether compounds).