The effect of fluidized bed hydrodynamics on jet attrition with a supersonic attrition nozzle has been studied in this paper. The aim is to determine a hydrodynamic condition that can help improve particle attrition. Two hydrodynamic zones were created by a specially designed fluidized bed. Experiments were conducted with a supersonic attrition jet either straddling both hydrodynamic zones, or completely enclosed within one hydrodynamic zone. It is found that jet grinding is most effective when the nozzle tip is located in a high fluidization velocity region and jet tip located in a low fluidization velocity region. Also, a larger nozzle is more effective in terms of the new surface area created. A baffle is found to improve the jet attrition process when it was inserted underneath the jet tip cavity. (C) 2012 Elsevier B.V. All rights reserved.