Novel electrocatalysts for methanol oxidation were prepared from two Pt-Ni multinuclear complexes, [Pt-2{Ni(NH2CH2CH2S)(2)}(4)]Cl-4 and [Pt(bpy){Ni(NH2CH2CH2S)(2)(bpy)}](NO3)(2) (bpy = 2,2'-bipyridine). They were adsorbed on a Au(111) surface by immersing the Au(111) electrode in solutions containing these complexes. The modified Au(111) electrodes were then subjected to potential cycling or heat-treatment at 200 degrees C and 300 degrees C so that organic ligands were decomposed and adsorbed complexes were converted to nanocomposites. For a comparison, Au(111) electrode modified by a Pt based nanocomposite prepared by using a di-platinum(II) complex ([Pt-2(terpy)(2)(mu-otdst)](2+) (terpy = 2.2':6',2 ''-terpyridine, H(2)otdst = 2-octylthio-4,6-disulfanyl-1,3,5-triazine)) as a starting molecule. The surface species were characterized by X-ray photoelectron spectroscopy (XPS) and scanning tunneling microscopy (STM) in addition to cyclic voltammetry (CV). Two-dimensional nano composites of monatomic height were observed by STM. The coverages of the nanocomposites were 2-8%. By repeating the complex adsorption and heat-treatment for five times, nanocomposites of higher coverage of 13-19% with monatomic height were formed on Au(111) surface. The resultant nanocomposites showed high activity for methanol oxidation reaction (MOR) with an improved CO-tolerance in a 0.1 M KOH aqueous solution containing 1 M CH3OH. (C) 2016 Elsevier B.V. All rights reserved.