Potassium tetrathionate is primarily used in biochemical research and analytical chemistry. It serves as a reagent in the study of thiol groups and disulfide bonds in proteins, helping to understand their structure and function. It is also employed in the preparation of other sulfur-containing compounds, which are essential in various chemical syntheses. Additionally, it finds application in the investigation of enzymatic reactions, particularly those involving sulfur metabolism. Its role in redox reactions makes it valuable in studying oxidative stress and antioxidant mechanisms in biological systems.