Diisooctylthiophosphinic acid is primarily used in the extraction and separation of metal ions, particularly in hydrometallurgical processes. It serves as an effective extractant for metals like cobalt, nickel, and copper from aqueous solutions, making it valuable in the mining and recycling industries. The compound is also employed in the purification of rare earth elements, which are critical for manufacturing electronics, magnets, and renewable energy technologies. Additionally, its role as a flotation agent in mineral processing helps enhance the recovery of valuable ores. Its selective binding properties make it a key component in the development of advanced separation techniques for industrial applications.