Reaction of chloroplatinum(II) and chloropalladium(II) complexes containing amine, pyridine (py), or phosphine ligands at or above room temperature with anhydrous CF₃SO₃H leads to formation of trifluoromethanesulphonato-O complexes, characterized spectroscopically. The complexes cis-[Pt(NH₃)₂(OSO₂CF₃)₂], trans-[Pt(NH₃)₂Cl(OSO₂CF₃)], [Pt(en)Cl(OSO₂CF₃)], (en = 1,2-diaminoethane), [Pt(dppe)(OSO₂CF₃)₂], [Pt(py)₂Cl(OSO₂CF₃)], [Pt(terpy)(OSO₂CF₃)][CF₃SO₃], (terpy = 2,2′: 6′,2″-terpyridine), trans-[Pd(NH₃)₂Cl(OSO₂CF₃)], [Pd(en)(OSO₂CF₃)₂], [Pd(bippy)(OSO₂CF₃)₂](bipy = 2,2′-bipyridine), and [Pd(PPh₃)₂(OSO₂CF₃)₂] were isolated. Aquation reactions of selected complexes showed that trifluoromethanesulphonate hydrolysis is rapid for complexes of both Pt^II and Pd^II. Bis(trifluoromethanesulphonato)platinum(II) complexes exhibit two consecutive rate processes, with k₁/k₂ca. 5, consistent with sequential hydrolysis of both anions. Preliminary investigations indicate that co-ordinated CF₃SO₃^– in these complexes may be substituted even by neutral co-ordinating O-donor solvents.