A new nonlinear optical material ammonium borodilactate [(NH4)(+)(C6H8BO6)(-)](ABL) has been synthesized. The synthesized compound was subjected to elemental analysis to confirm the constituent elements present in the compound. Single crystals of ABL have been grown by slow evaporation of saturated aqueous solution at room temperature. The grown crystals have been characterized by NMR, FT-IR and mass spectroscopic studies. The three-dimensional crystal structure has been solved by single crystal X-ray diffraction technique. TGA and DTA studies reveal good thermal stability. Kurtz powder test shows that the SHG efficiency is comparable to that of KDP. (C) 2003 Elsevier Science B.V. All rights reserved.