2-Hydroxy-4-methoxybenzophenone-5-sulfonic acid is a chemical substance, a benzophenone derivative, appearing as pale yellow crystals with a melting point of 170 °C and readily soluble in water. Its physicochemical properties include a content ≥99%, pH value 1.2-2.2, heavy metal content ≤5 ppm, and a high specific absorptivity (≥460 at 285 nm, ≥290 at 325 nm).

This compound is a broad-spectrum ultraviolet absorber, capable of absorbing both UV-A and UV-B wavelengths. It exhibits high thermal stability and non-toxicity, and is classified as a Class I sunscreen by the US FDA. It is widely used in sunscreen cosmetics (such as creams and lotions) and water-soluble inks and coatings. It can also be used as an anti-UV finishing agent for the anti-aging treatment of cotton fabrics and polyester fibers. Its preparation mainly involves the sulfonation reaction of dimethyl sulfate, and the process involves steps such as the synthesis of m-phenylenediamine, benzoyl chloride condensation, and sulfuric acid sulfonation.