The organothallium carboxylates, R2TlO2CR (R = C6F5, p-MeOC6F4, p-HC6F4, m-HC6F4 or o-HC6F4), prepared by reactions of appropriate halogenobis(polyfluorophenyl)thallium(III) compounds and sodium carboxylates, are considered to have associated structures with bridging carboxy- late groups. Thermal decomposition of R2TlO2CR (R = C6F5, p-MeOC6F4, p-HC6F4 or m-HC6F4) in boiling pyridine resulted in decarboxylation and formation of the corresponding tris(polyfluoro- phenyl)thallium compounds, which were isolated in analytically pure form as the complexes R3TI(diox) (R = C6F5, p-HC6F4 or m-HC6F4; diox = 1, 4-dioxan) and R3Tl(bpy) (R = C6F5 or p-MeOC6F4; bpy = 4, 4′-bipyridyl). However, no decomposition was observed when R = o-HC6F4. The ease of decarboxylation decreased in the sequence R = C6F5 > p-MeOC6F4 > p-HC6F4 ≈ m-HC6F4 ≫ o-HC6F4, and a possible mechanism is discussed. Pyrolysis of R2TlO2CR (R = C6F5, p-MeOC6F4, p-HC6F4, m-HC6F4 or o-HC6F4) at 310° under nitrogen in the absence of a solvent gave tris(poly- fluorophenyl)thallium compounds (R = C6F5, p-MeOC6F4, p-HC6F4 or m-HC6F4), isolated as the dioxan complexes, thallous fluoride and polyfluorobiphenyls and polyfluoropolyphenyls. In addition, decafluorobenzophenone was obtained when R = C6F5, methyl fluoride when R = p-MeOC6F4 and the corresponding tetrafluorobenzene C6H2F4 when R = p-HC6F4, m-HC6F4 or o-HC6F4. Chlorobis(2, 3, 5, 6-tetrafluoro-4-methoxyphenyl)thallium(m) was prepared by reaction of thallic chloride with 2, 3, 5, 6-tetrafluoro-4-methoxyphenyllithium, which was obtained from 2, 3, 5, 6-tetra- fluoroanisole and butyllithium.