Growth, structure and properties of the non-centrosymmetric hydrated borate CaN2B8O26H32

► CaN2B8O26H32 has been grown with sizes up to 9 × 8 × 5 mm3 for the first time. ► It is made up of CaO7 polyhedra, and [B4O5(OH)4]2− anions, NH4+ cations, and H2O molecules. ► UV-vis-NIR diffuse reflectance spectrum shows an UV absorption edge less than 190 nm. ► It exhibits the SHG efficiency of about half times that of KDP and is phase matchable.