The growth of a novel organic nonlinear optical (NLO) crystal of 2-aminopyridinium maleate (2APM) in larger size is reported for the first time by the slow evaporation method. Single-crystal X-ray diffraction analysis reveals that 2APM crystallizes in monoclinic system with space group Pc. The crystal was characterized by infrared (IR) and UV-vis-NIR spectra. Thermogravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. Powder second-harmonic generation was investigated to explore its NLO properties. The dielectric constant and dielectric loss of the specimen were also studied. The transmittance of 2APM has been used to calculate the refractive index (n) and both the real epsilon(r) and imaginary epsilon(i) components of the dielectric constant as functions of photon energy. (C) 2008 Elsevier B.V. All rights reserved.