The methanol dehydrogenation through the initial breaking of the O-H bond at Pt₇₉ nanoparticle is studied with the DFT method. The comparison with an ideal surface of Pt (111) is carried out. The most stable complexes were found for COН_х (x=1-4) particles adsorbed at low-coordinated atoms of nanocluster Pt₇₉, whereas no preference for adsorption at corners and edges for Н atom was found. The adsorption energies of COН_х species at corner and edge sites of platinum nanocluster increased on 0.2–0.7 eV in comparison with high-coordinated sites of regular Pt(111) surface. The stabilization effect of adsorption at nanoparticle decreases from corners to edges and then to the center of (111) facet. According to the reaction energy profile, the thermal effect of the formation of CH₃O at nanocluster becomes close to zero, in difference with endothermic effect (0.5 eV) on the regular Pt(111) surface. The exothermic effects for other reaction stages at platinum nanocluster, excluding CO desorption, increase on ~0.2-0.5 eV.