Benzoylcholine chloride is primarily used in biochemical research as a substrate for cholinesterase enzymes. It helps in studying the activity and inhibition of these enzymes, which are crucial in nerve signal transmission. This compound is also employed in diagnostic assays to measure cholinesterase levels in blood, aiding in the detection of certain medical conditions like pesticide poisoning or liver disease. Additionally, it serves as a tool in pharmacological studies to understand the mechanisms of drugs that target the cholinergic system.