Using the slow evaporation solution growth technique, a new compound of potassium sodium hydroxide borate hydrate (KSB) single crystal has been prepared. The title compound crystallized in a noncentrosymmetric hexagonal system with P6¯2c space group was confirmed by single crystal X-ray diffraction. The functional group was determined by using FTIR spectrum. The absorption spectrum shows an absorption edge at 265 nm with a band gap of 4.68 eV. The melting point of the material was found to be 105 °C using TG/DSC analysis. The frequency dependence of dielectric, ac conductivity and the relaxation of an ionically conducting crystal have been studied for different temperatures. Nonlinear optical measurement of the grown crystal can displays a SHG response which is almost equivalent to that of KDP. © 2016 Elsevier B.V.