Nonlinear optical crystal of CaN2B8O26H32 has been grown with sizes up to 9 x 8 x 5 mm(3) by the solvent evaporation method. The structure was determined by single-crystal X-ray diffraction and further characterized by powder X-ray diffraction and IR spectrum analysis. CaN2B8O26H32 crystallizes in the orthorhombic system, space group P2(1)2(1)2(1), with unit-cell parameters a=11.556(7) angstrom, b=12.583(8) angstrom, c=16.679(8) angstrom, z=4, V=2425.2(2) angstrom(3), R-1=0.0263, and wR(2)=0.0655. The structure is made up of CaO7 polyhedra, and [B4O5(OH)(4)](2-) polyborate anions, NH4+ cations, and H2O molecules. UV-vis-NIR diffuse reflectance spectrum is performed on the CaN2B8O26H32, which shows an absorption edge <190 nm in the UV region. Thermal properties were investigated by TG analyses. The powder second-harmonic generation intensity measured by the Kurtz-Perry method indicates that CaN2B8O26H32 has about half times that of KH2PO4. (C) 2011 Elsevier B.V. All rights reserved.