A model was developed to calculate the particle size distribution following the release of pressurised supercritical CO 2. The model combines several sub-models for the different stages of jet break-up and specifically addresses the possible formation of solid particles, which is important for CO 2 releases. The model was validated using experimental data available for CO 2 and for the release of other pressurised, superheated liquids. The model is able to describe the droplet formation process with sufficient accuracy. The values obtained for droplet diameter are mostly within 30% of the experimental data. Unfortunately, very little experimental information on the formation of solid CO 2 is available. However, the SMD calculated for CO 2 particles corresponds well with one available set of experimental data. © 2011 Elsevier Ltd.