In the present work the thermal stability of some members of the hydroxylamine family was studied using adiabatic calorimetry. The study included aqueous solutions of hydroxylamine free base, hydroxylamine hydrochloride, hydroxylamine sulfate, and hydroxylamine-o-sulfonic acid of concentrations typically used in industry. Also, the catalytic effect of metal surfaces of stainless steel, carbon steel, and titanium was studied. From the solutions Studied HA is the most reactive with higher maximum temperature, pressure, non-condensable pressure, and lower time to maximum rate. HA maximum heat rate is at least similar to3 times higher than that of the other solutions studied, and the pressure generation rate is similar to13 times higher. All decompositions were catalyzed by stainless steel, but only HA was catalyzed significantly by titanium metal. Solid hydroxylamine hydrochloride, hydroxylamine sulfate, and hydroxylamine-o-sulfonic acid exhibited stability up to similar to60 degreesC. Hydroxylamine 100% was not studied because it is not readily available, is not used industrially, and is known to be unstable at room temperature. A violent reaction was measured for solid hydroxylamine sulfate that generated a heat rate >500degreesC/min and pressure rate >5200 psia/min before the sample cell was completely destroyed by the generated pressure. (C) 2003 Elsevier B.V. All rights reserved.