The overall topic of this project is monitoring SO2 pollutants. Standards and regulations according to the content of hazardous particles in the exhaust gas change continuously which affects the maritime industry. In addition to the increasing restrictions and todays strong regulation, it has now become mandatory for the ships to self‐monitor the ESO (Emission of Sulfuric Oxides). Present solutions to monitor ESO are rather costly and as an alternative, we propose a cost‐efficient electrochemical sensor based on a potassium ion conductor. The purpose of the project is to develop a low‐cost sulfuric oxide sensor (SOS) based on a potassium (K)‐ion conductor with similar or better performance than commercially available solutions and to unravel the sensing mechanism in order to be able to optimize the sensing electrode. It is strongly believed that such a sensor will have a higher sensitivity and selectivity than the so far known best electrochemical sensors, as potassium is strongly alkaline and SO2 acidic. The success criteria is a sensor with a high output of at least 150 mV for a gas mixture containing 1 ppm SO2, which is much higher (approximately double value) than the known sulfuric oxide sensors based on sodium ion conductors, at a cost competitive price.