Many small-scale coal spontaneous combustion tests exist, but none of these appear to be comprehensive and definitive in terms of assessing the self-heating behaviour of coal at low temperatures from ambient to thermal runaway. Within this low temperature region there are a number of competing influences on the tendency of the coal to continue to gain heat. One of the key influences is the presence of moisture in the coal as this contributes to heat loss from evaporation. The presence of disseminated pyrite can contribute to heat gain from the additional exothermic reaction with oxygen in the presence of moisture. A new moist coal adiabatic oven test has been developed that can measure the influence of these parameters on the low temperature self-heating of coal. Examples of the experience gained from using this test clearly show the effects of moisture and pyrite on coal self-heating leading to thermal runaway. The results obtained have major consequences for the operational planning and management of the spontaneous combustion hazard.