Methylphosphonothioic dichloride is primarily utilized in the synthesis of organophosphorus compounds, which have significant applications in the field of chemical warfare agents. It serves as a key intermediate in the production of nerve agents, such as VX, due to its ability to form highly toxic phosphonothioate esters.

In addition to its military applications, this chemical is also employed in research and development for studying the mechanisms of nerve agents and developing antidotes or protective measures. Its reactivity with various nucleophiles makes it a valuable reagent in organic synthesis, particularly in the creation of phosphorus-containing ligands used in catalysis.

Furthermore, methylphosphonothioic dichloride is used in the development of pesticides and insecticides, where its derivatives can act as effective agents against a wide range of pests. However, its handling requires extreme caution due to its high toxicity and potential for misuse in harmful applications.