The thermal decomposition of copper hydroxy carbonate was examined using conventional rising temperature thermogravimetry and constant rate thermal analysis (CRTA). The low-pressure CRTA results showed that the two product gases, water and carbon dioxide, are evolved at different rates throughout the decomposition. A CRTA apparatus using infrared gas detectors was able to measure and control the evolution of these two gases independently and established that more water is evolved at the start of the reaction and more carbon dioxide near the end. The kinetics of the reaction were investigated using both rising temperature and CRTA results and reasonable agreement was found for the activation energy. However, the results for the reaction mechanism proved inconclusive. The development of the surface area as a function of the extent of reaction was investigated and found to be markedly non-linear. This fact is discussed in relation to the evolved gas results and a previously proposed mechanism for solid state decomposition reactions.