Disodium 1,5-naphthalenedisulfonate is a sodium salt of 1,5-naphthalenedisulfonic acid, characterized by two sulfonic acid groups (-SO₃H) attached to a naphthalene ring at the 1 and 5 positions. This compound typically appears as a white crystalline powder that is highly soluble in water, making it suitable for various applications. It is primarily recognized for its role in dyeing processes, acting as a mordant and enhancing the solubility of dyes, alongside serving as an intermediate in organic synthesis.