It has been well established that sustained combustion in ammonium nitrate water-based emulsions (AWEs) can only occur if the ambient pressure is held above some threshold value, usually referred to as the 'minimum burning pressure' (MBP). For the commercial explosives industry, a good knowledge of the MBP for particular AWE formulations is essential to estimate safe operating pressures for the associated manufacturing and handling processes. In these processes. AWE products are most often pumped in closed systems and at elevated temperature. While previous studies have established that the MBP can depend critically on major ingredients, its dependence on physical characteristics such as temperature and viscosity had never been investigated. Moreover, the consequences of alterations in measurement methodologies on the resulting measured MBP values had not been studied. In the present work, MBP measurements were performed for a number of AWE systems representative of those found in the commercial explosives industry. The effect of the presence or absence of certain ingredients on the MBP will be discussed. In particular, the influence of glass or polymeric microspheres and testing geometry on the combustion behaviour of some AWEs will be evidenced. Experimental results showing the effect of other physical factors such as initial product viscosity and temperature on the measured MBP values are also presented.