The authors of the title paper (Mater. Lett. 188 (2017) 156–158) has grown potassium sodium hydroxide borate hydrate (KSB) I single crystal using slow evaporation method. In this letter, crystal growth, unit cell measurement, FTIR and thermal analysis are described in order to prove that the grown single crystal (KSB) is a trustworthy material. © 2021 Elsevier B.V.