The complexes [PtMe2(NN)], NN = 2,2′-bipyridine = bipy, 1a; NN = di-2-pyridylamine = dpa, 1b; NN = di-2-pyridyl ketone = dpk, 1c, NN = 4,4′-bis(ethoxycarbonyl)-2,2′-bipyridine, bebipy, react with m-chloroperoxybenzoic acid to give the platinum(IV) complexes [Pt(OH)(O2C-3-C6H4Cl)Me2(NN)], NN = bipy, 2, or [Pt(OH)(OH2···O2C-3-C6H4Cl)Me2(NN)], NN = bipy, 3a; dpa, 3b; bebipy, 3d, or [Pt(OH)2Me2(dpkOH)]3[Pt(OH)(OH2)Me2(dpkOH)][H(O2C-3-C6H4Cl)2]·2MeOH, 43·5·2MeOH. The reactions are proposed to occur by a polar oxidative addition mechanism, followed in most cases by the coordination of water. Complex 3a crystallises as a supramolecular polymer, the compound 43·5·2MeOH crystallises as a supramolecular sheet structure, and 3d easily forms a gel, all through strong intermolecular hydrogen bonding.