Particle breakage by gas jet is encountered in many processes. Quite often it is necessary to evaluate the attrition performance of different equipment configurations at various flow conditions. Therefore, a simulation tool that can be applied for industrial scale devices can be very beneficial for process design and optimization. A mathematical model for particle attrition by high velocity gas jets is developed. The model utilizes an Eulerian-Eulerian approach for the gaseous and particulate phases coupled with the kinetic theory of granular flow and a novel attrition model connecting the solid phase properties and the granular temperature with the breakage rate. Modelling results allow the calculation of the grinding efficiency - a quantitative measure of the attrition performance. For validation purposes, the model is applied to a large number of cases that have been investigated experimentally. Simulation results demonstrate that the increase of the nozzle inlet pressure or the exit diameter for a forward step nozzle produces an increase of the grinding efficiency. In addition, the convergent-divergent nozzle is more efficient in breaking the particles than the nozzle that contains only the convergent section. (C) 2010 Elsevier Ltd. All rights reserved.