Using of EPR the laws of formation of various defects during mechanical treatment (MT) of powders of zinc oxide were considered. Formation of six different types of paramagnetic centers was established. The quantitative analysis of the changes of intensity (concentration of the centers in the sample) of EPR signals I-VI depending on conditions of MT (speed of rotation of jars of a mill, duration of MT, amount of entered additives, etc.) has allowed to establish interrelation between defects formation and temperature processes, which develop during MT. In the work the opportunities of an obtaining of samples with a necessary set of surface defects are discussed. (c) 2007 Elsevier B.V. All rights reserved.