This paper presents results concerning the use of a multitask cell coupled with a semi-industrial autoclave. A very good correlation was found between electrochemical measurements performed with the multitask cell and the three-electrode probe introduced in one of the autoclave's flanges. Using the permeation technique, a short time response system was obtained with the multitask cell. The observed performance of this system was consistent with the external one attached at the flange. It was observed that neither H2S nor cyanide alone increase the corrosion process in the alkaline wet H2S environment. The coupled action of these two contaminants is necessary to increase the hydrogen permeation through the steel wall of the equipment. As a consequence of this work, the multitask cell was successfully transferred to a PETROBRAS fluid catalytic cracking light end recovery unit.