One of the basic parameters characterizing the bond between a chemisorbed atom (or molecule) and the surface is its dissociation energy. It is difficult, however, to determine the bond energy and therefore it becomes necessary to turn to some other quantity, which is sufficiently close to the bond energy and which can be determined without much difficulty. Such a quantity is theheat of adsorption. Heat of adsorption is defined as the difference between the total energy of the adsorption system prior to and after the adsorption process, i.e., it equals the sum ofallenergy changes connected with adsorption. Thus the experimentally determined value for the heat of adsorption is obviously closely related to the bond energy of the chemisorbed particle, though this relation is not quite simple [1,2].