Scanning tunneling microscopy (STM) was used to investigate the surfaces of Pt(111) single crystals interfaced with YSZ and beta"-Al2O3 at atmospheric pressure. In both cases the STM imaged the reversible electrochemically controlled dosing (backspillover) of O2- species and of Na+ species on Pt(111) surface respectively, which both form a (12 x 12) hexagonal structure on the Pt(111) surface. On the mechanistic side, the STM has confirmed the backspillover mechanism of electrochemical promotion and metal support interactions. (c) 2006 Elsevier B.V. All rights reserved.