The kinetics of hydrogen desorption of the Mg(NH2)(2) + LiH mixture has been studied by measuring desorption rates at various temperatures. A desorption kinetic model based on the Gauss-diffusion equation derived from Fick's second law is proposed to interpret the dehydriding reaction. X-ray diffraction (XRD) and transmission electron microscopy (TEM) are carried out to assist the foundation of the model. Results show that the kinetic model obtained can basically describe the curvature of the experimental data and the dehydriding activation energy can be represented by the diffusion activation energy (104.3 KJ/mol) of H delta+ in the matrix. These indicate that the dehydrogenation can be described by H delta+ diffusing through the product layer between reactants. Based on the results, the methods of exploring suitable dopants to create more vacancies in the matrix and activating the N-H with an electromagnetic field are suggested to improve the desorption kinetics. (C) 2008 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.