Tetrafluoro-ethylene can be added to monoamines having oxyethyl or oxypropyl groups in aprotic polar solvents in the presence of alkali metals. The new monoamines obtained having the radicals tetrafluoro-ethyloxy-ethyl or tetrafluoro-ethyl-oxy-propyl are electrolyzed in anhydrous hydrofluoric acid, thus forming new monoamines in which all or nearly all hydrogen atoms of the starting compounds are replaced by fluorine.