Stirred media mill is one of the most energy-efficient types of grinding equipment for wet ultrafine grinding. Nevertheless, in a dry mode several problems arise, such as aggregation, agglomeration, sticking on the liners and the grinding media. The present paper deals with experiments carried out on the ultrafine cement grinding in dry mode at various grinding conditions in a stirred media mill to study the mechanochemical effect and the energy efficiency of the mill. Furthermore, comparative grinding experiments were carried out in a ball mill aimed at, first of all, studying the effect of the two grinding modes on the crystal structure of cement. It was found, based on the experimental results, that there is a mechanochemical effect on crystal structure of cement, mostly in the stirred media mill, as it was revealed by X-ray diffraction. Regarding the comparison of the ball mill and the stirred media mill, more energy-effective grinding was achieved in the latter. In addition, the experimental results from the stirred media mill made it possible to determine the effect of the rotor circumferential speed on the mechanical activation of cement. (C) 2012 Elsevier B.V. All rights reserved.