Nickel sulphide (NiS) was characterised using X-ray diffraction, thermal gravimetric analysis (TG) and differential scanning
calorimetry (DSC). The 'as received' Millerite, stoichiometric NiS, observed to be slightly nickel deficient, was found to
readily decompose in a nitrogen atmosphere at elevated temperatures (450C max.) to the sulphur deficient Godlevskite, Ni7S6. DSC and X-ray measurements demonstrated that the high temperature form of the Godlevskite was readily stabilised at room
temperature. The kinetics of the α-β re-transformation in Godlevskite were then investigated using DSC and were observed to
be first order.