The statistical lattice model has been proposed which permits one to take into account the change in the shape and surface morphology of the nanoparticle under the influence of the reaction media. The influence of monomolecular and dissociative adsorption on the particles equilibrium shape and surface morphology has been studied. It has been shown that by taking into account attraction "adsorbate-metal" the reshaping of the initial hemispheric particle into the truncated pyramidal one occurs induced by adsorption. similar to the experimentally observed reversible reshaping of active nanoparticles. (C) 2009 Elsevier B.V. All rights reserved.