We consider degassing of cylindrical sample containing dissolved hydrogen. The experiment is made by the thermodesorption method. In the corresponding boundary-value problem with nonlinear dynamic boundary conditions physical-chemical processes in the bulk and on the metal surface are taken into account: diffusion, desorption, solution, and capture by defects. Computational algorithm for desorption flux modelling is developed on the basis of difference approximations. The results of numerical modelling are presented. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.