The development of mechanoluminescence-based method for monitoring of size reduction processes in stirred media mill is described. Quartz particles are used as feed material that consists of aggregates and primary solid particles. Analysis of breakage in such system is problematic because it is very difficult to distinguish aggregates from primary particles. On the other hand, only stressing of primary particles between mill beads causes the mechanoluminescence impulses. Consequently, the use of mechanoluminescence can be very useful to characterize breakage in aggregates/primary particles system. The distribution of mechanoluminescence impulses depending on amplitude is measured at different grinding times and stirrer speeds. The obtained impulse number distribution can be described by means of two power functions with different exponents by low and high amplitudes. The first power function reflects the mechanical loading of fine primary particles. The second one corresponds to breakage of coarse particles. The impulses caused by stressing of fine primary particles are found to be suitable for dynamic characterization of size reduction in such system. (C) 2004 Elsevier B.V. All rights reserved.