Barium Diphenylamine Sulphonate (CAS No. 6211‑24‑1; Chemical Formula: C₁₂H₁₀BaNO₆S₂) is a fine, light-colored powder primarily used as a redox indicator. It plays a key role in analytical chemistry, particularly in titrations involving potassium dichromate. It typically appears in high purity analytical and reagent grades.