New chlorotrifluoroethylene telomers and process for preparing them. Chlorotrifluoroethylene is reacted, at a temperature ranging from -100.degree. to +40.degree. C., with a fluoroxy compound of formula R.sub.x --CF.sub.2 OF, wherein R.sub.x represents among others a perhalogenated alkyl radical containing from 1 to 10 carbon atoms. There are obtained telomer mixtures having, among others, the following formulae: R.sub.x --CF.sub.2 --O--(M).sub.n --F; R.sub.x --CF.sub.2 --O--(M).sub.n --O--CF.sub.2 --R.sub.x ; R.sub.x --(M).sub.n --F; R.sub.x (M).sub.n --R.sub.x ; R.sub.x --CF.sub.2 --O--(M).sub.n --R.sub.x and F--(M).sub.n --F; wherein M is CF.sub.2 --CFCL and "N" ranges from 2 to 20. Most of these telomers are new compounds.