Mercury (II) and lead (II) ions, but not mercury (l) and thallium (I), react with both the nitrosyIdisulphonate, ON(S03)22- and the hydroxylaminedisulphonate dianions, ON(S03)22−-, to yield the corresponding metal sulphate and a mixture of sulphate and sulphite ions. Silver (I) ions are reduced to the metal by both anions, but reacts with potassium imidodisulphonate, HN(SO3K)2, and tripotassium imidodisulphonate, KN(S03K)2, to yield trisilver imidodisulphonate, Ag3NS2O6, and disilver potassium imidodisulphonate, Ag2KNS2O6. The reaction of some related salts are also reported. Mechanisms for some of the decompositions, and stoichiometric equations are proposed. No metal salts of hydroxylaminedisulphonates, HON(SO3M)2 were isolated. The silver imidodisulphonate salts failed to react with both alkyl and aryl halides. A series of N, N-bis-(arylsulphonyl)hydroxylamines, (p-XC6H4S2)2N0, were synthesised (X = H, Me, MeO, Cl and F). The species (p-XC6H4S2)2N0, p-XC6H4S2NO and p-XC6H4S2 are proposed as intermediates during the oxidation of the bis-species with PbO2, silver (I,III) oxide, AgO, MnO2. Pb(O2CMe)4 or nitric acid to N, N, 0-tris-(arylsulphonyl)hydroxylamines, p-XC6H4S2)2N0S2C6H4X-p and nitrate ion. A mechanism involving hydroxylamine is ruled out. I. r. and n.m.r. spectra show that the tris-species are hydroxylamines, R2NOR, rather than amine oxides, R3NO, and the structure is considered by a comparison with (CF208)2NOH and (CF3)2NO. The e.s.r. spectra of the tris-species in benzene indicates the presence of a nitroxide radical. The bis-species are found to decompose to the tris-hydroxylamine and the corresponding arenesulphonic acid, while the tris-species decompose to the sulphonic acid. Oligomerisation of cyclohexene is observed during the oxidation of bis-hydroxylamines, while with bases, such as pyridine, the hydroxylamine is converted to a mixture of (RSO2)2NH pyridine-N-oxide and a pyridinium arylsulphonate. N, N, 0-tris-(Alkyl-sulphonyl) hydroxylamines could not be isolated. Nitrosylarene-sulphinates, p-XC6H4SO2NO are proposed as intermediates but could not be isolated from the reactions of nitrosyl chloride and nitrogen (II) oxide with arylsulphonylhydroxylamines. p-XC6H4SO2NHOH, (p-XC6H4SO2)2NOH and p-XC6H4SO2NH2 (X=H, CH3) are all are converted by NOCl to p-XC6H4SO2Cl, but (p-XC6H4S02)2N0S02C6H4X-p and (p-XC6H4SO2)2NH are unaffected. Oxidation of C6H5SO2NHOH by a range of oxidants yielded, C6H5SO2Cl, C6H5SO3H, or (C6H5SO2)2NOSO2C6H5, but not C6H5SO2NO. Diene cycloaddition products of p-XC6H4SO2NO could not be isolated. p-CH3C6H4SO2Na is converted by nitrosyl chloride to p-CH3C6H4SO2Cl rather than to p-CH3C6H4SO2NO. (p-CH3C6H4SO2)2NH is inert to a wide range of oxidants. Both (p-XC6H4S02)2NOH and (p-XC6H4S02)2N0S02C6H4X-p initiate free-radical halogenation by dichlorine and dibromine, but not by diiodine, of benzene and cyclohexane. Simple carboxyamides also initiate free-radical chlorination of the same substrates. (N-aryl-N-arylsulphonyl) hydroxylamines were oxidised by PbO2 and Pb(02CMe)4, but not MnO2, to a mixture of the corresponding [N- aryl-N, O -bis(aryl sulphonyl)]hydroxylamine, nitrobenzene and azoxybenzene. The tris-species appears to contain the nitroxide radical, ArS02N(0)Ar1. A similar mechanism to that for the oxidation of (p-XC6H4S02)2N0H is proposed.