Recent experimental work has shown that the field electron microscope (FEM) and the field ion microscope (FIM) can also serve as an in situ catalytic flow reactor. Platinum field emitter (model catalyst, grain diameter similar to 700 Angstrom) expose different nano single-crystal planes with well-defined crystallographic orientations. Isothermal, non-linear dynamic processes of the CO + O-2 reaction on Pt have been studied as well as the formation of face-specific adsorption islands, mobility of reaction/diffusion fronts and creation of chemical waves. Analysis of Pt surface with a local atom resolution of 4-6 Angstrom shows The availability of a sharp boundary between the mobile COads and O-ads fronts. It has been found that the back phase transition of Pt surface (100) hex <----> 1 x 1 plays an initiating function in the generation of chemical waves along certain crystallographic orientations of Pt surface. The reaction zone maximum active in CO2 formation, with a width of up to 40 A, has been discovered between adsorbed COads and O-ads beds. The adsorption of O-2 and the reaction of molecular O-2ads(2-) State as well as an atomic Oads State with CO on the Pt(100)-(hex) and the Pt(100)-(1 x 1) single crystal surface have been studied with HREELS and thermal desorption spectroscopy (TDS) techniques.