This compound is primarily used in biochemical research as a substrate for cholinesterase enzymes. It helps in studying enzyme activity and kinetics, particularly in assays that measure the function of acetylcholinesterase and butyrylcholinesterase. The hydrolysis of thiocholine iodide produces thiocholine, which can be detected using colorimetric or electrochemical methods, making it valuable in diagnostic and analytical applications. Additionally, it is employed in neuroscience research to investigate cholinergic systems and their role in neurotransmission. Its use extends to toxicology studies for evaluating the effects of cholinesterase inhibitors, such as organophosphates and carbamates.