Diisoamyl phosphate is primarily used as a solvent extractant in the separation and purification of metals, particularly in hydrometallurgical processes. It is effective in selectively extracting metal ions such as uranium, vanadium, and rare earth elements from aqueous solutions. This property makes it valuable in the mining and recycling industries for recovering valuable metals from ores or waste materials. Additionally, it serves as a plasticizer in the production of polymers, enhancing flexibility and durability in materials like PVC. Its application in lubricant formulations also improves the performance and stability of industrial lubricants under high-temperature and high-pressure conditions.