The mini-autoclave or mini closed pressure vessel test has been evaluated in view of its potential use as a screening tool for chemical reactivity hazards. The mini-autoclave is a temperature controlled reaction system enabling the small-scale determination of the stability or reactivity of materials. It is shown that the mini-autoclave is a useful tool to assess the relative effect of conditions and compositions and that a number of reaction specific parameters can be determined. Utilization of the equipment for absolute determination of the reactivity of materials is less likely. The experimental results can be used for a qualitative assessment of the effect of (non-)confined conditions on the decomposition properties and the relative impact of increased acidity and impurity levels on the decomposition properties. The results can also be used to select and define test conditions for larger scale experiments and to enable a safety assessment on the defined larger scale experiments. (C) 2004 Elsevier Ltd. All rights reserved.