The crystal structure of tris(2-hydroxyethyl)ammonium bromide, [HN(CH2CH2OH)(3)]BT, was determined as rhombohedral by single crystal X-ray diffractometer. The final R value was found to be 0.032 for 576 observed reflections. The crystal consists of layers of hydrogen-bonded cations, [HN(CH2CH2OH)(3)](+) and anions, Br-. Within a layer every cation donates and every anion accepts three hydrogen bonds. In the cation, trifurcated intramolecular hydrogen bonds are formed due to the surrounding of the hydrogen atom bonded to the N atom by the 2-hydroxyethyl groups.