MgH2 powder samples have been irradiated with 45 key B3+ ions with different ion fluencies ranging from 10(12) to 10(16) ions/cm(2). Irradiation effects have been estimated by SRIM calculations. To characterize induced modifications and its influence on the hydrogen desorption behavior of MgH2, X-ray diffraction (XRD) analysis, particle size analysis and temperature programmed desorption (TPD) have been used. Changes of TPD spectra with irradiation conditions suggest that there are several mechanisms involved in desorption process which depend on defect concentration and their interaction and ordering. It has been demonstrated that the changes in near-surface area play the crucial role in hydrogen desorption kinetics. The results also confirm that there is possibility to control the thermodynamic parameters by controlling vacancies concentration in the systems. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.