Thullium(III) fluoride is an inorganic compound with the chemical formula TmF<sub>3</sub>.
It can be produced by reacting thulium(III) sulfide and hydrofluoric acid, followed by thermal decomposition:
Thulium(III) oxide reacts with fluorinating agents such as hydrogen fluoride, nitrogen trifluoride xenon difluoride to create thullium(III) fluoride as well, although the reaction with nitrogen trifluoride is incomplete and produces a mixture of TmOF and TmF<sub>3</sub>.