Aqueous solutions of hydrazine reduce strong oxidizing agents in dilute acid medium to give nitrogen, ammonia and hydrazoic acid. The nature and relative abundance of the oxidation products depend upon reaction conditions and the oxidanti. KIRK AND BROWNER have classified different oxidants as mono-electron removers or di-electron removers and stated that nitrogen is the main oxidation product when oxidants of the second type are employed. Some of the redox processes involve both types of electron removal simultaneously. HIGGINSON et aZ.3 suggested that a further distinction be made between those oxidants which could form a complex of the type Oxidant + NH2-NHa = Oxidant + NH2-NH3 before the reaction and those which could not. The theory is only partially satisfactory as some reagents are known 1 to behave differently under different experimental conditions, such as varying acidity, temperature or even the manner of mixing the reagents. The suggestion that two 2-electron transfers shotild quantitatively oxidize hydrazine to Na is substantiated by its oxidation with thallium(II1) in dilute acid solutiona, with co-ordination complex formation preceding the electron transfer. Iodine monochloride is about S y. ionized4 and the equilibrium is instantancously adjusted if some I+ ions are removed in complex formation. Since I+ is much stronger acid than H30+, the reaction of iodine monochloride with hydrazine in acid medium could be represented as H4N2 :H+ + ICla-= H4Nz:I+ + H+(aq) + 2 Clwhich will oxidize hydrazine to H2Nz H4Nz:I+ = H3N2+2 H++I-(slow) HsN4 is then oxidized to nitrogen by more iodine monochloride or free iodine present in solution HzNz + IC12-= N2+2 H+(aq)+I-+z Cl-HnNz + I2 = N2+2 H+(aq) +2 I-The last two reactions are apparently fast because of the relative instability of HaNa.