A CI electronic microbalance which allowed sample weights up to 5 g to be measured with a maximum sensitivity of 1 mug has been used to develop a new constant rate thermal analysis (CRTA) technique. This permitted a constant rate of change of weight Absolute value of C greater-than-or-equal-to 10 mug min-1. Moreover, it has been extended to constant rate jump thermal analysis (CRJTA). The microbalance is attached to a conventional system of vacuum and gas storage that allowed work to be carried out under vacuum or under controlled atmosphere. The performance of the equipment was checked by studying both the thermal decomposition of CaCO3 and the recombination reaction of silicon and nitrogen, producing Si3N4.