In this paper, we report the thermal activation of zeolite with the addition of a thermal shock step. We observed that thermal shock caused the zeolite particles to transform into smaller particles. By fitting a log-normal distribution to the particle sizes on the basis of SEM images, we obtained the average diameter of the particles as a result of thermal shock, which was approximately 1/4 of the initial particle diameter. We propose a model to explain the mechanism of fragmentation as a result of thermal shock We also introduce a criterion for fragmentation of brittle materials. The proposed model and criterion qualitatively explain why the diameters of zeolite particles resulting from thermal shock are approximately 1/4 of the initial particle diameter. (C) 2016 Elsevier B.V. All rights reserved.