2, 3, 5, 6-Tetrafluorophenylmercuric trifluoroacetate and acetate, 1, 4-bis(tri-fluoroacetatomercuri)tetrafluorobenzene, and 1, 4-di(acetatomercuri)tetraffuorobenzene have been prepared by mercuration of 1, 2, 4, 5-tetrafluorobenzene with mercuric trifluoroacetate or acetate while 2, 3, 5, 6-tetrafluorophenglmercuric chloride and acetate, 1, 4-di(chloromercuri)tetrafluorobenzene, and 1, 4-di(acetatomercuri)tetrafluorobenzene have been obtained from the corresponding trifluoroacetates by metathesis reactions. The di(chloromercuri) derivative has also been isolated from reaction of thallous tetrafluoroterephthalate with mercuric chloride. Bis(2, 3, 5, 6-tetrafluorophenyl)mercury has been prepared by rearrangement of 2, 3, 5, 6-tetrafluorophenglmercuric trifluoroacetate with iodide ions, and by mercuration of 1, 2, 4, 5-tetrafluorobenzene with tetrabromomercurate(II) ions under alkaline conditions. The latter reaction also gave a low yield of 1, 4-bis(2, 3, 5, 6-tetrafluorophenylmercuri)tetrafluorobenzene, which was identified by n.m.r. spectroscopy, and by degradation with mercuric chloride. The carbon-oxygen stretching frequencies of the new organomercuric carboxylates are indicative of unidentate carboxylate coordination.