Polyethylene glycol tert-octylphenyl ether X-405 is a nonionic surfactant widely employed in both industrial and research settings. Belonging to the polyethylene glycol (PEG) ether family, this compound features a hydrophilic head and a lipophilic tail, making it suitable for use in emulsions, detergents, and solubilizers. Notably beneficial in membrane protein studies, it aids in dissolving and stabilizing proteins for structural analysis. Moreover, Polyethylene glycol tert-octylphenyl ether X-405 is utilized in various applications, such as drug delivery systems, nanotechnology, and diagnostic analysis. Due to its emulsifying and solubilizing properties, it is also used in the production of microemulsions, ointments, and lotions. It is important to note that ingestion or inhalation of this compound can be toxic, necessitating proper handling and safety precautions.