Poly(styrene sulfonic acid) is widely used as a proton-conducting material in fuel cells, where it serves as a key component in proton exchange membranes (PEMs). Its high proton conductivity and chemical stability make it suitable for facilitating the movement of protons in these systems. Additionally, it is employed in water treatment processes as a cation exchange resin, effectively removing metal ions and other contaminants from water. In the field of electronics, it is utilized as a dopant in conductive polymers, enhancing their electrical properties for applications in sensors and organic electronics. It also finds use in coatings and adhesives, where its sulfonic acid groups improve adhesion and durability. Furthermore, it is applied in biomedical research for modifying surfaces to enhance biocompatibility or for drug delivery systems due to its ability to interact with biological molecules.