It is an acid-base indicator, adsorption indicator, the chemical formula is C27H28O5SBr2, soluble in ethanol, ether, methanol and dilute hydroxide alkali solution. Slightly soluble in benzene, toluene and xylene, slightly soluble in water, almost insoluble in petroleum ether. The English abbreviation is BTB. It is often used as a respiratory reagent for aquatic organisms in biological experiments.

Bromothymol blue is widely used in textile, leather, paint, ink and other industries. It can be used as a dye, pigment and indicator to impart a deep blue color to certain materials.