Abstract: The present invention relates to MOFs for use in radiotherapy. More particularly, the invention provides a particle comprising a MOF, optionally at least one targeting moiety and at least one radionuclide; a composition comprising said particle; said particle or composition for use as a medicament; said particle or composition for use in a method for the treatment of a proliferative disease; said particle or composition for use in a method for the treatment of a chronic inflammatory disease; and a kit comprising a particle comprising a MOF, an optional targeting moiety, and a radionuclide cation.