NOVELTY - The process of etching an area selected from a transparent conductive oxide layer deposited on a substrate, comprises electrochemically setting off the area in the presence of a polarized microelectrode, positioning the microelectrode near the surface of the selected zone, contacting an electrochemical solution with the selected zone, and polarizing the microelectrode and the conductive metal oxide layer. The microelectrode is an ultramicroelectrode, a probe of scanning electrochemical microscopy and a probe of atomic force microscopy.    USE - The process is useful for etching an area selected from a transparent conductive oxide layer deposited on a substrate, where the transparent conductive oxide is useful as an electrode material in detectors, bioelectronic sensors, touch screens, solar cells, LCDs, LEDs, organic electroluminescent devices, glass, mirrors or lenses.    ADVANTAGE - The process is capable of rapidly, economically and accurately etching an area selected from a transparent conductive oxide layer deposited on a substrate with good reproducibility and without generating residues on the substrate and damaging the film or substrate.    DETAILED DESCRIPTION - The process of etching an area selected from a transparent conductive oxide layer deposited on a substrate, comprises electrochemically setting off the area in the presence of a polarized microelectrode, positioning the microelectrode near the surface of the selected zone, contacting an electrochemical solution with the selected zone, and polarizing the microelectrode and the conductive metal oxide layer. The microelectrode is an ultramicroelectrode, a probe of scanning electrochemical microscopy and a probe of atomic force microscopy. The electrochemical solution comprises a weak acid having a dissociation constant (pKa) of 4-9, a compound adapted to chelate (complex) with a metal ion, and a protic solvent comprising water, deionized water, distilled water, acidified water, acidified deionized water and acidified distilled water. The potential imposed to the microelectrode is 7 V and to indium tin oxide layer is -0.1 V. The process further comprises an additional step of moving the microelectrode close to the selected area of the conductive metal oxide layer. The substrate further comprises a conductive material layer and a semiconductor or insulator layer deposited on the conductive metal oxide. An INDEPENDENT CLAIM is included for a conductive metal oxide layer.    DESCRIPTION OF DRAWING(S) - The diagram shows a schematic view of a process for etching an area selected from a transparent conductive oxide layer deposited on a substrate (Drawing includes non-English language text).