Following the indications of earlier work, the use of a closed pressure vessel test (a mini-autoclave system) to estimate the explosive properties of organic compounds has been investigated. The dependent variable was an explosivity ranking derived from the results of a propagation of detonation test, a heating under confinement test and a deflagration test. Tentative criteria have been derived to allow the following conclusions: Not detonable Not Class 1 No explosive properties with respect to transport classification The criteria are based upon the maximum rate of pressure rise observed in the mini-autoclave and the temperature at which this occurs. They offer a more efficient screen than the decomposition energy criteria which are currently used for initial assessment of explosive properties. The importance of event temperature suggests that existing classification tests may be underestimating heating under confinement and deflagration hazards. In this case, maximum rates of pressure rise from a closed pressure vessel test might be a better basis of classification, at least for supply if not transport. Further work is necessary to test the proposed screening criteria and to assess the use of a closed pressure vessel test as a means of classification.