Bulk single crystals of pentachloropyridine (PCP) were grown by the Bridgman-Stockbarger method. The single crystalline nature of the grown crystals was confirmed using powder X-ray diffraction (XRD) techniques. These were transparent in the 315-2000nm range. The second harmonic generation (SHG) efficiency of polycrystalline materials using Kurtz powder technique was found to be twice that of the well-known organic nonlinear optical (NLO) material, urea. The mixing behavior of PCP with succinonitrile (SCN) and its effect on SHG and micro-hardness of PCP, along with the physicochemical properties of different compositions of PCP and SCN system were studied in detail. Bulk single crystals of the PCP solid solution containing 0.02 mole fraction of SCN have also been grown using the Bridgman-Stockbarger technique. (c) 2005 Elsevier B.V. All rights reserved.