Abstract: An electrochemical sensor designed to be employed in equipment of petrochemical plants made of an electrochemical cell without polarization which includes an outer tube or first electrode and an internal rod or second electrode. Both first and second electrodes being provided with wires for external electrical contact. The first and second electrodes being separated by a standard electrolytic solution for the oxidation of the nascent hydrogen which is generated by the corrosion reactions caused by sulfur compounds in contact with the hydrogen-permeable metal which constitutes the equipment of petrochemical plants. The sensor is coupled to a zero resistance ammeter which assesses the electrical current generated by the oxidation of the nascent hydrogen and provides a plot of electrochemical noise.