Abstract: Hydrazine is a simple nitrogen compound that is used extensively in the manufacture of several important industrial products including plastic blowing agents, growth retardants and pharmaceuticals and in rocket propellants. It is a toxic compound causing fatty liver and in some cases liver necrosis, CNS disturbances and tumours in various organs. It is remarkably stable even though it has high (positive) heat of formation. Molecular modelling analyses show that although the reaction in which hydrazine decomposes to nitrogen and hydrogen is spontaneous, the relatively large kinetic barrier imparts stability to hydrazine molecule. However, since the reaction is highly exothermic, once it starts, it would speed up quickly. The metabolites THOPC and pyruvate hydrazone have relatively low LUMO-HOMO differences indicating that the two compounds would be the most reactive metabolites of hydrazine and the presence of negatively charged regions on its surface indicates that the metabolite can be subject to electrophilic attack.