The influence of the shape of limestone particles on impact crushing parameters has been investigated by testing single particles in a high-resolution impact analyzer. The measurements conducted included the contact time and force, the transferred energy, the fragment size and shape distribution as well as the energy utilization. The particles tested were classifled in seven different shape classes that ranged from spheres and cubes to plate-shaped and acicular bodies. The results show that the measured parameters are significantly influenced by the particle shape. These differences are caused by an additional orientation phase of an irregularly shaped particle prior to the main impact. Usually, the impact bar of the crusher hits one of the corners first, accelerates, rotates the particle and disintegrates a part of it occasionally. For spherical and cubical particles the contact forces and transferred energy are the highest and the contact time is the lowest. These results suggest that the mechanical design of impact crushers could be made on the basis of testing spheres or cubes, which would provide a safety factor in the design. Regarding the size distribution of the fragments, both the upper diameter and size modulus of a truncated Rosin-Rammler-Sperling-Bennet distribution are the lowest for spherical particles while no clear trend was found in respect to the distribution modulus. The comparison of the fragment shape distributions shows, except for the coarser fragments, hardly an influence of the initial particle shape on the smaller fragments. The energy utilization is the lowest with spherical and cubical bodies and rises with increased elongation and flatness of the feed particles. (C) 2008 Elsevier Ltd. All rights reserved