Single crystals of a new polymorph of lead succinate Pb(C4H4O4) with nonlinear optical (NLO) properties have been successfully grown by gel diffusion technique. The crystallinity of the grown crystals has been analyzed by powder X-ray diffraction studies. Single crystal X-ray diffraction analysis shows that the compound belongs to monoclinic system and is having a compact three-dimensional polymeric structure. Fourier transform infrared (FT-IR) and Fourier transform Raman (FT-Raman) spectral studies have been performed to identify the functional groups. Thermo gravimetric analysis (TGA) and differential thermal analysis (DTA) were used to study its thermal properties. The optical transmittance window and the lower cut off wavelength of the crystal have been identified by UV-visible transmittance studies. Dielectric constant and dielectric loss of the grown crystals were evaluated for the frequency range 300 Hz-3 MHz. The second harmonic output intensity was tested using the Kurtz and Perry powder method and was found to be 3.5 times as large as potassium dihydrogen phosphate (KDP). (C) 2011 Elsevier B.V. All rights reserved.