A theoretical description of the debonding process is presented by using Griffith’s criterion of rupture, that is applied to the balance of free energy during the debonding of a spherical filler particle from the polymer matrix. Debonding processes in model composites prepared from epoxy and polyethylene matrix filled with glass beads of various sizes have been investigated by acoustic emission analysis. The amplitude distribution for all AE events at the debonding stress was calculated and fitted by a Weibull distribution function. By comparing the results of debonding stress with the measured amplitudes, the influence of the different filler coatings on the energy balance of debonding can be discussed on the basis of the Griffith theory.