Experimental data on the attrition of fluidized cracking catalyst (FCC) powder in the jetting region of a fluidized bed indicate that the attrition rate is proportional to the orifice velocity raised to the power 3. This dependence is analysed here by coupling the kinetics of attrition, based on single-particle impact attrition testing, with a hydrodynamic model of the jetting region, from which the profiles of particle velocity and concentration can be calculated. It is shown that the approach predicts a power index which is in reasonable agreement with the experimental data, and it can therefore identify the relative contributions to attrition arising from the material response and jet hydrodynamics.