Methylhydrazine sulfate is primarily utilized as a chemical intermediate in the synthesis of pharmaceuticals, pesticides, and other hydrazine derivatives. It serves as a stable salt form of methylhydrazine, which is widely used as a high-energy rocket propellant in spacecraft and military bipropellant systems, often paired with oxidizers like dinitrogen tetroxide. Additionally, it functions as a reducing agent in various organic reactions. Due to its highly toxic and carcinogenic properties, its use is strictly regulated, necessitating rigorous safety protocols for handling, storage, and disposal.